The DOI matches its Crossref record; 281 of the 281 references it cites were found in a registry or an index; 19 of the 147 sources its claims cite were checked for support.
The biological and clinical significance of emerging SARS-CoV-2 variants
Open accessAbstract
The past several months have witnessed the emergence of SARS-CoV-2 variants with novel spike protein mutations that are influencing the epidemiological and clinical aspects of the COVID-19 pandemic. These variants can increase rates of virus transmission and/or increase the risk of reinfection and reduce the protection afforded by neutralizing monoclonal antibodies and vaccination. These variants can therefore enable SARS-CoV-2 to continue its spread in the face of rising population immunity while maintaining or increasing its replication fitness. The identification of four rapidly expanding virus lineages since December 2020, designated variants of concern, has ushered in a new stage of the pandemic. The four variants of concern, the Alpha variant (originally identified in the UK), the Beta variant (originally identified in South Africa), the Gamma variant (originally identified in Brazil) and the Delta variant (originally identified in India), share several mutations with one another as well as with an increasing number of other recently identified SARS-CoV-2 variants. Collectively, these SARS-CoV-2 variants complicate the COVID-19 research agenda and necessitate additional avenues of laboratory, epidemiological and clinical research. In this Review, the authors describe our latest understanding of the emergence and properties of SARS-CoV-2 genetic variants, particularly those designated as WHO (World Health Organization) ‘variants of concern’. They focus on the consequences of these variants for antibody-mediated virus neutralization, with important implications for reinfection risk and for vaccine effectiveness.
Overview
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Written from the paper’s full text.
TL;DR
This review synthesizes SARS-CoV-2 evolution, spike structure and the biological/clinical significance of the four WHO variants of concern as of June 2021: Alpha, Beta, Gamma and Delta. It shows that recurrent spike mutations increase transmissibility and immune evasion, reducing neutralization by monoclonal antibodies and vaccinee plasma, and calls for integrated genomic, neutralization and vaccine-efficacy surveillance.
Key findings
- Four VOCs emerged independently: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2). Alpha was estimated to be ~50% more transmissible than prior UK variants and associated with an estimated 50% increased mortality; Beta was estimated to be 50% more transmissible than preceding lineages; Gamma was estimated to cause 3–4 times higher virus levels and 1.1-fold to 1.8-fold higher mortality; Delta spread to 54 countries and replaced Alpha in the UK and USA.
- Neutralization escape varied by variant. Beta showed 3-fold to 10-fold reduced susceptibility to 46% and >10-fold reduced susceptibility to 22% of convalescent plasma samples; mRNA vaccinee plasma showed 45% with 3-fold to 10-fold and 30% with >10-fold reduced Beta neutralization. Delta showed 3-fold to 10-fold reduced susceptibility to 45% and >10-fold to 5% of convalescent plasma samples, while ~15% of BNT162b vaccinee plasma had 3-fold to 10-fold reduced Delta neutralization. Alpha was rarely associated with reduced convalescent plasma susceptibility but showed 3-fold to 10-fold reduced susceptibility to ~15% of mRNA vaccinee plasma samples.
- Vaccine efficacy against VOCs was reduced in several studies: BNT162b retained >90% efficacy against Alpha in Israel and Qatar; Beta efficacy was 72% in a Qatar cohort and 75% in a test-negative case-control study; Delta efficacy was ~85% for BNT162b and ~60% for AZD1222 in UK case-control studies. In trials, AZD1222 efficacy against Beta was 10% in South Africa, and NVX-CoV2373 efficacy was 49% against Beta and 86.3% against Alpha versus 96.4% against non-Alpha variants.
- Key mutations include D614G, which rose to near 100% global prevalence by June 2020; N501Y, which increases ACE2 affinity; E484K, which reduces susceptibility to several monoclonal antibodies and plasma; and non-spike mutations that antagonize innate immunity, with Alpha and Beta showing mean 112-fold and 8-fold reduced susceptibility to type I interferons, respectively, compared with an early pandemic virus.
Methods
- Narrative review creating a framework for SARS-CoV-2 variants by describing evolution, spike protein structure/function, laboratory characterization methods, biological and epidemiological properties of VOCs/VOIs, and required research responses; data summarized as of June 2021.
- Synthesizes genomic surveillance data from more than two million partially or fully sequenced virus isolates, in vitro selection and neutralization experiments using pseudotyped viruses, VSV-based chimeric viruses, full-length recombinant SARS-CoV-2 and cultured isolates, deep mutational scanning, and vaccine efficacy trials, test-negative case-control studies and cohort studies.
- Neutralization results were pooled in the Stanford University Coronavirus Antiviral & Resistance Database and summarized as <3-fold, 3–10-fold and >10-fold reductions compared with control viruses.
Limitations
- The paper states that as of June 2021 it is uncertain whether current lineage-based variant classification will be sustainable, and that classifying variants by component mutations may become challenging if recurrent mutations increase.
- The paper notes unresolved questions, including whether neutralizing antibodies are the most important protective mechanism versus memory B cells, Fc-effector functions and T cell immunity, and whether updated immunogens can broaden responses in animal models more predictive of humans.
- Evident from the text: this is a synthesis as of June 2021, so later variants and data are not included; neutralization estimates pool results across pseudotyped, chimeric and infectious virus assays, and some distributions are approximate because they include results reported only as aggregate mean fold reductions.
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Claims the paper makes
69 Not checked yet · 10 Own interpretation · 8 Partly supported · 3 No basis given · accuracy not yet measured
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“However, in three other studies, the median reduction in neutralizing activity was between onefold and threefold 102,214,215 .”
What the sources say
- Partly supportedcites [102] Supasa, P. et al. Reduced neutralization of SARS-CoV-2 B.1.1.7 variant by convalescent and vaccine sera. Cell 184, 2201–2211 (2021). sourceExperimental — accuracy not yet measured
The Results section ('Neutralization activity of convalescent plasma and vaccine sera'; page not provided) reports a 2.9-fold reduction for convalescent plasma and 2.1- and 2.5-fold reductions for AstraZeneca vaccine sera, all within the claimed range. These are geometric means, not medians, and the reported Pfizer vaccine-serum reduction is 3.3-fold, outside that range. This source cannot establish the results of the other two cited studies. (LLM, conf=0.85)
- Supportedcites [214] Planas, D. et al. Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization. Nature 596, 276–280 (2021). source
In “Sensitivity of Delta to convalescent sera” (page unavailable), the paper reports median neutralization titres and says Delta titres were fourfold lower than Alpha titres and sixfold lower than D614G titres. Those comparisons imply an approximately 1.5-fold reduction for Alpha relative to D614G, within the claimed onefold-to-threefold range. This paper is one of the three studies cited; it need not itself report the other two. (LLM, conf=0.84)
- Not checked yetcites [215] Mlcochova, P. et al. SARS-CoV-2 B.1.617.2 Delta variant emergence and vaccine breakthrough. Preprint at Research Square https://www.researchsquare.com/article/rs-637724/v1 (2021).
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Partly supported
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“Of plasma samples obtained from persons receiving one of the mRNA vaccines, 45% had 3-fold to 10-fold and 30% had >10-fold reduced Beta variant neutralizing activity 97,104,117,121,151,204,208,209,222,223 (fIg.5).”
What the sources say
- Not checked yetcites [97] Chen, X. et al. Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab646 (2021). This paper presents a systematic review and meta-analysis of in vitro neutralization studies of SARS-CoV-2 variants by convalescent and vaccinee plasma. source
- Partly supportedcites [104] Zhou, D. et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine induced sera. Cell 184, 2348–2361 (2021). sourceExperimental — accuracy not yet measured
The Results section, “Neutralization of B.1.351 by vaccinee serum” (page unavailable), reports that serum from Pfizer-BioNTech vaccine recipients had a 7.6-fold lower geometric mean neutralization titer against B.1.351 than against Victoria. It does not report that 45% of mRNA-vaccine samples had a 3- to 10-fold reduction or that 30% had a greater-than-10-fold reduction. (LLM, conf=0.88)
- Partly supportedcites [117] Chen, R. E. et al. Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies. Nat. Med. 27, 717–726 (2021). sourceExperimental — accuracy not yet measured
The Results report reduced neutralization of the Beta (B.1.351) variant by sera from BNT162b2 mRNA-vaccine recipients: a 10-fold reduction in geometric mean activity in one assay and a 6- to 9-fold reduction in another. They do not report the claimed distribution of samples—45% with 3- to 10-fold reductions and 30% with reductions greater than 10-fold—or results from more than one mRNA vaccine. (LLM, conf=0.88)
plain- Asserted: passes — The authors put it forward as true.
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The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“By contrast, among plasma samples obtained from recipients of the AZD1222 vaccine, higher proportions displayed reduced neutralizing activity against this variant 100,209,214 .”
What the sources say
- Partly supportedcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). sourceExperimental — accuracy not yet measured
The Results section, “Protection from B.1.617.1 and B.1.617.2 by vaccine serum” (page unavailable), reports that neutralization titers in serum from Oxford-AstraZeneca (AZD1222) recipients were 4.3-fold lower against B.1.617.2 (Delta) than against the Victoria strain. That supports reduced neutralizing activity, but the passage reports a reduction in the group's geometric mean titer, not a higher proportion of individual samples showing reduced activity. (LLM, conf=0.83)
- Partly supportedcites [209] Wall, E. C. et al. Neutralising antibody activity against SARS-CoV-2 VOCs B.1.617.2 and B.1.351 by BNT162b2 vaccination. Lancet 397, 2331–2333 (2021). sourceExperimental — accuracy not yet measured
The main text (page not given; appendix p. 2 cited) reports that a higher proportion of samples from BNT162b2 recipients had low neutralising titres against B.1.617.2 (Delta) than against wild-type virus. It does not report this result for AZD1222 recipients; searches for AZD1222 and ChAdOx1 found no such analysis in our copy. (LLM, conf=0.86)
- Partly supportedcites [214] Planas, D. et al. Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization. Nature 596, 276–280 (2021). sourceExperimental — accuracy not yet measured
In “Sensitivity of Delta to sera from vaccinated individuals,” the paper reports that after one AstraZeneca (AZD1222) dose, only 9% of recipients’ sera neutralized Delta, compared with 74% for D614G and 61% for Alpha. The claim omits the dose qualification: four weeks after a second dose, sera from 95–100% of AstraZeneca recipients neutralized all four strains. The paper tested sera, rather than describing the samples as plasma. (LLM, conf=0.86)
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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- Partly supported
None of the sources cited for this claim have been checked yet.
In the paper
“The past several months have witnessed the emergence of four SArS-cov-2 variants of concern (Alpha, beta, Gamma and Delta)”
- Also stated in: § SARS-CoV-2 evolution · plain
“The four variants of concern, the Alpha variant (originally identified in the UK), the Beta variant (originally identified in South Africa), the Gamma variant (originally identified in Brazil) and the Delta variant (originally identified in India)”
What the sources say
- Not checked yetcites [27] Rambaut, A. et al. Preliminary genomic characterisation of an emergent SARS-CoV-2 lineage in the UK defined by a novel set of spike mutations. Virological https://virological.org/t/563 (2020).
- Not checked yetcites [16] Tegally, H. et al. Detection of a SARS-CoV-2 variant of concern in South Africa. Nature 592, 438–443 (2021). This molecular epidemiological study charts the spread of the beta variant in South Africa and shows that it resulted from selective evolutionary forces. source
- Not checked yetcites [19] Faria, N. R. et al. Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil. Science 372, 815–821 (2021). This paper presents an analysis showing that the Gamma variant is about twofold more transmissible than previous variants in Manaus, Brazil, and that it poses an increased risk of reinfection compared with previous variants. source
plain- Asserted: passes — The authors put it forward as true.
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- Also stated in: § SARS-CoV-2 evolution · plain
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The increasing number of SArS-cov-2 variants share a repertoire of mutations that is enabling the virus to spread despite rising population immunity while maintaining or increasing its replication fitness.”
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“In a post-hoc analysis of a NVX-CoV2373 clinical trial, vaccine efficacy was 86.3% against Alpha variants compared with 96.4% against non-Alpha variants 212 (TABLe 2).”
What the sources say
- Not checked yetcites [212] Heath, P. T. et al. Safety and efficacy of NVX-CoV2373 Covid-19 vaccine. N. Engl. J. Med. https://doi.org/10.1056/NEJMoa2107659 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“By the second quarter of 2021, the Alpha variant accounted for the majority of infections in the USA and many European countries 23,196 .”
What the sources say
- Not checked yetcites [23] Hodcroft, E. CoVariants: SARS-CoV-2 mutations and variants of interest (NextStrain). CoVariants https://covariants.org/ (2021).
- Not checked yetcites [196] Mullen, J. L. et al. Outbreak.info https://outbreak.info/citation (2020).
plain- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“It was also associated with threefold to eightfold higher upper-airway levels [199][200][201]”
What the sources say
- Not checked yetcites [199] Golubchik, T. et al. Early analysis of a potential link between viral load and the N501Y mutation in the SARS-COV-2 spike protein. Preprint at bioRxiv https://doi.org/10.1101/2021.01.12.20249080 (2021). source
- Not checked yetcites [200] Kidd, M. et al. S-variant SARS-CoV-2 lineage B1.1.7 is associated with significantly higher viral loads in samples tested by ThermoFisher TaqPath RT-qPCR. J. Infect. Dis. 223, 1666–1670 (2021). source
- Not checked yetcites [201] Borges, V. et al. Tracking SARS-CoV-2 lineage B.1.1.7 dissemination: insights from nationwide spike gene target failure (SGTF) and spike gene late detection (SGTL) data, Portugal, week 49 2020 to week 3 2021. Eur. Surveill. 26, 2100131 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“and an estimated 50% increased mortality 194,195,202 .”
What the sources say
- Not checked yetcites [194] Davies, N. G. et al. Increased mortality in community-tested cases of SARS-CoV-2 lineage B.1.1.7. Nature 593, 270–274 (2021). source
- Not checked yetcites [195] Challen, R. et al. Risk of mortality in patients infected with SARS-CoV-2 variant of concern 202012/1: matched cohort study. BMJ 372, n579 (2021). source
- Not checked yetcites [202] Grint, D. J. et al. Case fatality risk of the SARS-CoV-2 variant of concern B.1.1.7 in England, 16 November to 5 February. Eur. Surveill. 26, 2100256 (2021). source
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“The Beta variant was estimated to be 50% more transmissible than the lineages that preceded it 16 .”
What the sources say
- Not checked yetcites [16] Tegally, H. et al. Detection of a SARS-CoV-2 variant of concern in South Africa. Nature 592, 438–443 (2021). This molecular epidemiological study charts the spread of the beta variant in South Africa and shows that it resulted from selective evolutionary forces. source
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“In this trial, AZD1222 displayed a non-statistically significant reduction in efficacy against the Alpha variant (70%; 95% confidence interval (CI) 44-85%) compared with earlier variants (82%; 95% CI 68-89%) 213 .”
What the sources say
- Not checked yetcites [213] Emary, K. R. W. et al. Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 variant of concern 202012/01 (B.1.1.7): an exploratory analysis of a randomised controlled trial. Lancet 397, 1351–1362 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“In a study of vaccine trial participants, plasma samples were associated with a median reduction in neutralizing activity of ninefold to the Alpha variant compared with an earlier UK variant 213 .”
What the sources say
- Not checked yetcites [213] Emary, K. R. W. et al. Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 variant of concern 202012/01 (B.1.1.7): an exploratory analysis of a randomised controlled trial. Lancet 397, 1351–1362 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“The Alpha variant has displayed 3-fold to 10-fold reduced susceptibility to approximately 15% of plasma samples from recipients of an authorized mRNA vaccine 97,102,121,148,149,152,159,204,208,209 .”
What the sources say
- Not checked yetcites [97] Chen, X. et al. Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab646 (2021). This paper presents a systematic review and meta-analysis of in vitro neutralization studies of SARS-CoV-2 variants by convalescent and vaccinee plasma. source
- Not checked yetcites [102] Supasa, P. et al. Reduced neutralization of SARS-CoV-2 B.1.1.7 variant by convalescent and vaccine sera. Cell 184, 2201–2211 (2021). source
- Not checked yetcites [121] Wang, P. et al. Antibody resistance of SARS-CoV-2 variants B.1.351 and B.1.1.7. Nature 593, 130–135 (2021). This paper presents a comprehensive analysis of the effects of Alpha and Beta variant mutations on antibody neutralization. source
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“many additional SArS-cov-2 variants sharing mutations and biological features with these variants are also increasingly being identified.”
plaincorrelational- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“As of June 2021, the Beta variant accounts for more than 50% of infections in many countries in sub-Saharan Africa 23,196 .”
What the sources say
- Not checked yetcites [23] Hodcroft, E. CoVariants: SARS-CoV-2 mutations and variants of interest (NextStrain). CoVariants https://covariants.org/ (2021).
- Not checked yetcites [196] Mullen, J. L. et al. Outbreak.info https://outbreak.info/citation (2020).
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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None of the sources cited for this claim have been checked yet.
In the paper
“In cohort studies from Israel and Qatar, the BNT162b vaccine also retained greater than 90% efficacy against this variant 210,211 (TABLe 2).”
What the sources say
- Not checked yetcites [210] Haas, E. J. et al. Impact and effectiveness of mRNA BNT162b2 vaccine against SARS-CoV-2 infections and COVID-19 cases, hospitalisations, and deaths following a nationwide vaccination campaign in Israel: an observational study using national surveillance data. Lancet 397, 1819–1829 (2021). source
- Not checked yetcites [211] Abu-Raddad, L. J., Chemaitelly, H. & Butt, A. A. Effectiveness of the BNT162b2 Covid-19 Vaccine against the B.1.1.7 and B.1.351 Variants. N. Engl. J. Med. 385, 187-189 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“L452R has resulted in 3-fold to 10-fold reduced susceptibility to about one third of convalescent and vaccinee plasma samples”
What the sources say
- Not checked yetcites [164] Greaney, A. J. et al. Antibodies elicited by mRNA-1273 vaccination bind more broadly to the receptor binding domain than do those from SARS-CoV-2 infection. Sci. Transl Med. 13, eabi9915 (2021). source
- Not checked yetcites [165] Ferreira, I. et al. SARS-CoV-2 B.1.617 mutations L452 and E484Q are not synergistic for antibody evasion. J. Infect. Dis. https://doi.org/10.1093/infdis/jiab368 (2021). source
- Not checked yetcites [166] Zhang, L. et al. Comparison of 10 emerging SARS-CoV-2 variants: infectivity, animal tropism, and antibody neutralization. Preprint at Research Square https://doi.org/10.21203/rs.3.rs-492659/v1 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Whereas most emerging mutations reduce the protective effects of neutralizing antibodies generated by infection and vaccination”
plaindirect- Asserted: passes — The authors put it forward as true.
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- Based: unclear — It is unclear why the paper says it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Epidemiological studies suggest that it was approximately 50% more transmissible than previously circulating UK variants 191,197,198 .”
What the sources say
- Not checked yetcites [191] Volz, E. et al. Assessing transmissibility of SARS-CoV-2 lineage B.1.1.7 in England. Nature 593, 266–269 (2021). This analysis demonstrates the increased transmissibility of the alpha variant. source
- Not checked yetcites [197] Leung, K., Shum, M. H., Leung, G. M., Lam, T. T. & Wu, J. T. Early transmissibility assessment of the N501Y mutant strains of SARS-CoV-2 in the United Kingdom, October to November 2020. Eur. Surveill. 26, 2002106 (2021). source
- Not checked yetcites [198] Davies, N. G. et al. Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England. Science 372, eabg3055 (2021). source
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“Several Alpha variant sub-lineages have acquired additional mutations that might increase the risk of reinfection and vaccine failure, including the RBD mutations E484K, F490S and S494P (ref. 158 ).”
What the sources say
- Not checked yetcites [158] Grabowski, F., Preibisch, G., Giziński, S., Kochańczyk, M. & Lipniacki, T. SARS-CoV-2 variant of concern 202012/01 has about twofold replicative advantage and acquires concerning mutations. Viruses 13, 392 (2021). source
hedgedconditional- Asserted: passes — The authors put it forward as true.
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- Based: passes — The paper gives a reason why it holds.
In the paper
“Reinfections with the Beta variant occurred commonly during a phase IIb trial of the NVX-CoV2373 vaccine performed in South Africa as approximately one third of infections in both the vaccine and placebo arms were reinfections 216 .”
What the sources say
- Not checked yetcites [216] Shinde, V. et al. Efficacy of NVX-CoV2373 Covid-19 vaccine against the B.1.351 variant. N. Engl. J. Med. 384, 1899–1909 (2021). This post-hoc analysis of a clinical trial shows that the beta variant was frequently responsible for reinfections in South Africa. source
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“The Beta variant has displayed 3-fold to 10-fold reduced susceptibility to 46% and >10-fold reduced susceptibility to 22% of convalescent plasma samples compared with early pandemic variants 97,101,104,121,124,203,204,[218][219][220] (fIg.5).”
What the sources say
- Not checked yetcites [97] Chen, X. et al. Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab646 (2021). This paper presents a systematic review and meta-analysis of in vitro neutralization studies of SARS-CoV-2 variants by convalescent and vaccinee plasma. source
- Not checked yetcites [101] Moyo-Gwete, T. et al. Cross-reactive neutralizing antibody responses elicited by SARS-CoV-2 501Y.V2 (B.1.351). N. Engl. J. Med. 384, 2161–2163 (2021). This experimental study shows that the plasma from persons infected with the beta variant can usually neutralize pre-variant viruses. source
- Not checked yetcites [104] Zhou, D. et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine induced sera. Cell 184, 2348–2361 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“Among nine BNT162b vaccine breakthrough infections in an Israeli case-control study, eight were with the Beta variant even though the Alpha variant predominated during the study period 226 .”
What the sources say
- Not checked yetcites [226] Kustin, T. et al. Evidence for increased breakthrough rates of SARS-CoV-2 variants of concern in BNT162b2-mRNA-vaccinated individuals. Nat. Med. 27, 1379–1384 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Of plasma samples from persons receiving the AZD1222 vaccine, 42% had 3-fold to 10-fold and 54% had >10-fold reduced Beta variant neutralizing activity 104,214,224 (fIg.5).”
What the sources say
- Not checked yetcites [104] Zhou, D. et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine induced sera. Cell 184, 2348–2361 (2021). source
- Not checked yetcites [214] Planas, D. et al. Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization. Nature 596, 276–280 (2021). source
- Not checked yetcites [224] Madhi, S. A. et al. Efficacy of the ChAdOx1 nCoV-19 Covid-19 vaccine against the B.1.351 variant. N. Engl. J. Med. 384, 1885–1898 (2021). This post-hoc analysis of a clinical trial shows that AZD1222 appeared ineffective at preventing infection with the beta variant. source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“The two variants probably diverged from a common ancestor between August and October 2020 (fIg.1).”
What the sources say
- Not checked yetcites fIg.1
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“The Beta variant has also been associated with reduced vaccine efficacy (TABLe 2).”
What the sources say
- Not checked yetcites TABLe 2
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Of plasma samples from persons receiving one of the two authorized mRNA vaccines, about 60% had 3-fold to 10-fold and 5% had >10-fold reduced neutralizing activity 97,103,117,167,217,230 (fIg.5).”
What the sources say
- Not checked yetcites [97] Chen, X. et al. Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab646 (2021). This paper presents a systematic review and meta-analysis of in vitro neutralization studies of SARS-CoV-2 variants by convalescent and vaccinee plasma. source
- Not checked yetcites [103] Dejnirattisai, W. et al. Antibody evasion by the P.1 strain of SARS-CoV-2. Cell 184, 2939–2954 (2021). source
- Not checked yetcites [117] Chen, R. E. et al. Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies. Nat. Med. 27, 717–726 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“In a phase II trial in South Africa of AZD1222 in which 39 HIV-negative patients became infected with the Beta variant, the estimated vaccine efficacy was just 10% 224 .”
What the sources say
- Not checked yetcites [224] Madhi, S. A. et al. Efficacy of the ChAdOx1 nCoV-19 Covid-19 vaccine against the B.1.351 variant. N. Engl. J. Med. 384, 1885–1898 (2021). This post-hoc analysis of a clinical trial shows that AZD1222 appeared ineffective at preventing infection with the beta variant. source
hedgedn = 39- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Among the FDA EUA-approved mAbs, the Delta variant is associated with high-level reduced bamlanivimab susceptibility 100,214 .”
What the sources say
- Not checked yetcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). source
- Not checked yetcites [214] Planas, D. et al. Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization. Nature 596, 276–280 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Of convalescent plasma samples obtained from persons infected with early pandemic variants or with the Alpha variant, about 20% had 3-fold to 10-fold and 10% had >10-fold reduced neutralizing activity 97,103,117,203,217,228,229 (fIg.5).”
What the sources say
- Not checked yetcites [97] Chen, X. et al. Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab646 (2021). This paper presents a systematic review and meta-analysis of in vitro neutralization studies of SARS-CoV-2 variants by convalescent and vaccinee plasma. source
- Not checked yetcites [103] Dejnirattisai, W. et al. Antibody evasion by the P.1 strain of SARS-CoV-2. Cell 184, 2939–2954 (2021). source
- Not checked yetcites [117] Chen, R. E. et al. Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies. Nat. Med. 27, 717–726 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“The Gamma variant contains the RBD mutations N501Y, E484K and K417T (ref. 19 ).”
What the sources say
- Not checked yetcites [19] Faria, N. R. et al. Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil. Science 372, 815–821 (2021). This paper presents an analysis showing that the Gamma variant is about twofold more transmissible than previous variants in Manaus, Brazil, and that it poses an increased risk of reinfection compared with previous variants. source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“In a phase III trial of the Janssen Ad26.COV2.S vaccine, vaccine efficacy in South Africa was 52% and 64% against moderate to severe COVID-19 with onset at least 14 and 28 days after administration, respectively 225 .”
What the sources say
- Not checked yetcites [225] Sadoff, J. et al. Safety and efficacy of single-dose Ad26.COV2.S vaccine against COVID-19. N. Engl. J. Med. 384, 2187–2201 (2021). source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“Conversely, plasma from 22 persons infected with the Beta variant retained partial or full neutralizing activity against variants from earlier waves of the pandemic in all but three persons 101 .”
What the sources say
- Not checked yetcites [101] Moyo-Gwete, T. et al. Cross-reactive neutralizing antibody responses elicited by SARS-CoV-2 501Y.V2 (B.1.351). N. Engl. J. Med. 384, 2161–2163 (2021). This experimental study shows that the plasma from persons infected with the beta variant can usually neutralize pre-variant viruses. source
plainn = 22- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“A similar distribution in the reduction in neutralizing activity was observed in plasma samples from recipients of the AZD1222 vaccine 103 .”
What the sources say
- Not checked yetcites [103] Dejnirattisai, W. et al. Antibody evasion by the P.1 strain of SARS-CoV-2. Cell 184, 2939–2954 (2021). source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“In a phase II trial of NVX-CoV2373 in South Africa in which 38 of 41 infections were caused by the Beta variant, the estimated vaccine efficacy was 49% 216 .”
What the sources say
- Not checked yetcites [216] Shinde, V. et al. Efficacy of NVX-CoV2373 Covid-19 vaccine against the B.1.351 variant. N. Engl. J. Med. 384, 1899–1909 (2021). This post-hoc analysis of a clinical trial shows that the beta variant was frequently responsible for reinfections in South Africa. source
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“The resistance profile of the Gamma vari ant to the FDA EUA-approved mAbs is similar to that of the Beta variant 103,109,217,227,228 (TABLe 1).”
What the sources say
- Not checked yetcites [103] Dejnirattisai, W. et al. Antibody evasion by the P.1 strain of SARS-CoV-2. Cell 184, 2939–2954 (2021). source
- Not checked yetcites [109] Copin, R. et al. The monoclonal antibody combination REGEN-COV protects against SARS-CoV-2 mutational escape in preclinical and human studies. Cell 184, 3949–3961 (2021). source
- Not checked yetcites [217] Hoffmann, M. et al. SARS-CoV-2 variants B.1.351 and P.1 escape from neutralizing antibodies. Cell 184, 2384–2393.e12 (2021). source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“The ability of mAb, convalescent plasma and vaccinee plasma to neutralize the Eta variant has been infrequently studied 118,166 .”
What the sources say
- Not checked yetcites [118] Liu, J. et al. BNT162b2-elicited neutralization of B.1.617 and other SARS-CoV-2 variants. Nature 596, 273–275 (2021). source
- Not checked yetcites [166] Zhang, L. et al. Comparison of 10 emerging SARS-CoV-2 variants: infectivity, animal tropism, and antibody neutralization. Preprint at Research Square https://doi.org/10.21203/rs.3.rs-492659/v1 (2021). source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Of plasma samples from recipients of an mRNA vaccine, about 30% display 3-fold to 10-fold reduced neutralizing activity 230,235 .”
What the sources say
- Not checked yetcites [230] Pegu, A. et al. Durability of mRNA-1273 vaccine-induced antibodies against SARS-CoV-2 variants. Science https://doi.org/10.1126/science.abj4176 (2021). source
- Not checked yetcites [235] Zhou, H. et al. B.1.526 SARS-CoV-2 variants identified in new york city are neutralized by vaccine-elicited and therapeutic monoclonal antibodies. mBio https://doi.org/10.1128/mBio.01386-21 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Among plasma samples obtained from recipients of the BNT162b vaccine, approximately 15% displayed 3-fold to 10-fold reduced neutralizing activity against the Delta variant 100,118,214 (fIg.5).”
What the sources say
- Not checked yetcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). source
- Not checked yetcites [118] Liu, J. et al. BNT162b2-elicited neutralization of B.1.617 and other SARS-CoV-2 variants. Nature 596, 273–275 (2021). source
- Not checked yetcites [214] Planas, D. et al. Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization. Nature 596, 276–280 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Nonetheless, in vitro neutralization studies and epidemiological vaccine efficacy studies indicate weaker protection against emerging variants for most of the non-mRNA vaccines.”
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“Moreover, regardless of the vaccine received, reductions in vaccine-elicited humoral immunity is likely to be clinically significant for persons with impaired immunity as a result of underlying disease, immunosuppressive drugs or older age [241][242][243][244] .”
What the sources say
- Not checked yetcites [241] Collier, D. A. et al. Age-related immune response heterogeneity to SARS-CoV-2 vaccine BNT162b2. Nature https://doi.org/10.1038/s41586-021-03739-1 (2021). source
- Not checked yetcites [242] Furer, V. et al. Immunogenicity and safety of the BNT162b2 mRNA COVID-19 vaccine in adult patients with autoimmune inflammatory rheumatic diseases and in the general population: a multicentre study. Ann. Rheum. Dis. https://doi.org/10.1136/annrheumdis-2021-220647 (2021). source
- Not checked yetcites [243] Haidar, G. et al. Immunogenicity of COVID-19 vaccination in immunocompromised patients: an observational, prospective cohort study interim analysis. Preprint at medRxiv https://doi.org/10.1101/2021.06.28.21259576 (2021). source
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Except for several mAb preparations (for example, bamlanivimab/etesevimab), most antiviral compounds are likely to retain activity against each of the current VOCs and VOIs.”
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“However, it remains rare, accounting for a small proportion of infections even in the Philippines 196 .”
What the sources say
- Not checked yetcites [196] Mullen, J. L. et al. Outbreak.info https://outbreak.info/citation (2020).
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“The Lambda variant (C.37) has a unique set of spike mutations including L452Q and F490S within the RBD and the NTD deletion Δ246-252 (ref.237 ).”
What the sources say
- Not checked yetcites [237] Wink, P. L. et al. First identification of SARS-CoV-2 Lambda (C.37) variant in southern Brazil. Preprint at medRxiv https://doi.org/10.1101/2021.06.21.21259241 (2021). source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“There have also been no reports of variants with mutations in the enzymatic targets of therapy that would reduce susceptibility to remdesivir or to the RNA-dependent RNA polymerase and protease inhibitors in clinical development.”
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: unclear — It is unclear why the paper says it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, because of the presence of the RBD mutations L452R and E484Q, the Kappa variant has a somewhat greater ability to evade humoral immunity than the Delta variant.”
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“Moreover, as the spike protein has been found to contain multiple cytotoxic and helper T cell epitopes, it will be important that as many of these as possible are included in future vaccine preparations 89 .”
What the sources say
- Not checked yetcites [89] Grifoni, A. et al. SARS-CoV-2 Human T cell Epitopes: adaptive immune response against COVID-19. Cell Host Microbe 29, 1076–1092 (2021). This paper presents a systematic review of published SARS-CoV-2 helper and cytotoxic T cell epitopes. source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“This analysis demonstrates the increased transmissibility of the alpha variant.”
What the sources say
- Not checked yetcites Volz, E. et al.
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“An mRNA vaccine that incorporated most of the spike mutations present in the Beta variant (mRNA-1273.351;Moderna) was recently reported to increase both pre-variant and Beta variant-specific neutralizing antibody titres when administered as a booster to mice that had previously been immunized with mRNA-1273 (ref.246 ).”
What the sources say
- Not checked yetcites [246] Wu, K. et al. Variant SARS-CoV-2 mRNA vaccines confer broad neutralization as primary or booster series in mice. Preprint at bioRxiv https://doi.org/10.1101/2021.04.13.439482 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“As summarized in this Review, neutralizing antibody titres against pre-variant and variant SARS-CoV-2 isolates correlate with protection from infection in epidemiological studies.”
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: unclear — It is unclear why the paper says it holds.
- It may state two separate claims as one. 33
- Probably not a substantial claim. 8
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“Of 34 convalescent plasma samples from persons infected with the Alpha variant, 59% had 3-fold to 10-fold reduced neutralizing activity and 18% had >10-fold reduced neutralizing activity to the Beta variant 99,104,221 .”
What the sources say
- Partly supportedcites [99] Faulkner, N. et al. Reduced antibody cross-reactivity following infection with B.1.1.7 than with parental SARS-CoV-2 strains. Elife 10, e69317 (2021). sourceExperimental — accuracy not yet measured
The Results and Discussion report reduced neutralisation of B.1.351 (Beta) by B.1.1.7 (Alpha) sera, with a 7.7-fold change and a range of 3.4- to 17.9-fold. They do not report the claimed breakdown of 59% and 18%; the Materials and methods describe 29 patients with B.1.1.7 infection, not 34. (LLM, conf=0.88)
- Partly supportedcites [104] Zhou, D. et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine induced sera. Cell 184, 2348–2361 (2021). sourceExperimental — accuracy not yet measured
The Results section reports reduced neutralization of Beta (B.1.351), but the 34 convalescent samples were collected before Alpha (B.1.1.7) emerged. The paper reports a separate Alpha-infected group of 13 patients, not 34, and does not report the claimed 59% and 18% breakdown for that group. Page numbers are unavailable in our copy. (LLM, conf=0.86)
- Partly supportedcites [221] McCallum, M. et al. SARS-CoV-2 immune evasion by the B.1.427/B.1.429 variant of concern. Science 373, 648–654 (2021). sourceExperimental — accuracy not yet measured
The Results section (page unavailable) reports reduced neutralization of the Beta variant (B.1.351) by convalescent plasma. But its nine donors were likely infected with Wuhan-1 or a related virus, not Alpha, and it does not report the claimed 34 samples or the 59% and 18% breakdowns. (LLM, conf=0.84)
plaindirectn = 34- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Partly supported
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“By June 2021, the Gamma variant accounted for a high proportion of infections in several South American and Caribbean countries 196 and 10% of US infections 33 .”
What the sources say
- Not checked yetcites [196] Mullen, J. L. et al. Outbreak.info https://outbreak.info/citation (2020).
- Partly supportedcites [33] Bolze, A. et al. Rapid displacement of SARS-CoV-2 variant B.1.1.7 by B.1.617.2 and P.1 in the United States. Preprint at medRxiv https://doi.org/10.1101/2021.06.20.21259195 (2021). sourceExperimental — accuracy not yet measured
The Results (page not available) report that Gamma reached 15% of sequenced US samples by May 28–June 3, 2021. This supports a substantial US presence around June, but not the cited figure of 10% of infections. The South American and Caribbean statement carries a different citation and is not assessed here. (LLM, conf=0.85)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“As the Gamma variant was associated with a surge of infections in a region of Brazil estimated to have achieved a high infection rate, it is suspected of being able to infect and cause illness in persons previously infected with other variants 19,29,30 .”
What the sources say
- Supportedcites [19] Faria, N. R. et al. Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil. Science 372, 815–821 (2021). This paper presents an analysis showing that the Gamma variant is about twofold more transmissible than previous variants in Manaus, Brazil, and that it poses an increased risk of reinfection compared with previous variants. source
Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
- Partly supportedcites [29] Buss, L. F. et al. Three-quarters attack rate of SARS-CoV-2 in the Brazilian Amazon during a largely unmitigated epidemic. Science 371, 288–292 (2021). sourceExperimental — accuracy not yet measured
Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
- Supportedcites [30] Sabino, E. C. et al. Resurgence of COVID-19 in Manaus, Brazil, despite high seroprevalence. Lancet 397, 452–455 (2021). source
Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Supported
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“In addition, the mRNA vaccines appear to often elicit memory B cells that undergo somatic hypermutation, which should broaden the response to viruses with variant spike proteins 239,240 .”
What the sources say
- Partly supportedcites [239] Wang, Z. et al. Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection. Nature 595, 426–431 (2021). sourceExperimental — accuracy not yet measured
The Memory B cells section reports continued somatic hypermutation after infection, and the Discussion says mRNA vaccination enhances memory B-cell responses and likely protects vaccinated convalescent individuals against variants (page not specified). But the paper says vaccine-driven expansion of persistent memory clones does not accumulate large numbers of additional mutations. It does not establish that mRNA vaccines often elicit this mutation-driven broadening in people without prior infection. (LLM, conf=0.88)
- Partly supportedcites [240] Turner, J. S. et al. SARS-CoV-2 mRNA vaccines induce persistent human germinal centre responses. Nature https://doi.org/10.1038/s41586-021-03738-2 (2021). sourceExperimental — accuracy not yet measured
The paper reports persistent germinal-centre responses after mRNA vaccination and finds that a small fraction of cross-reactive B-cell clones had higher somatic hypermutation, suggesting a pre-existing memory B-cell origin (Abstract; page not provided). It does not show that vaccination often elicits memory B cells that undergo new somatic hypermutation, or establish that this process broadens responses to variant SARS-CoV-2 spike proteins. (LLM, conf=0.85)
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Partly supported
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“Of convalescent plasma samples, about 40% had 3-fold to 10-fold and 15% had >10-fold reduced neutralizing activity 100,122,234 .”
What the sources say
- Partly supportedcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). sourceExperimental — accuracy not yet measured
The Results section, ‘Neutralization of B.1.617.1 by convalescent serum’ (page unavailable), reports reduced neutralization of the Kappa variant in convalescent samples, including a 3.9-fold reduction in geometric mean titer for B.1.617.1-B. It does not report that about 40% of samples had 3- to 10-fold reductions or that 15% had reductions greater than 10-fold; a group mean cannot establish those sample-level proportions. (LLM, conf=0.84)
- Partly supportedcites [122] Edara, V. V. et al. Infection and Vaccine-Induced Neutralizing-Antibody Responses to the SARS-CoV-2 B.1.617 Variants. N. Engl. J. Med. 385, 664–666 (2021) sourceExperimental — accuracy not yet measured
The paper’s main text (page unavailable) reports reduced neutralizing activity against B.1.617.1 (Kappa) in convalescent serum, including a lower geometric mean titer than against WA1/2020. It does not report that about 40% of samples had a 3- to 10-fold reduction or that 15% had a greater-than-10-fold reduction. (LLM, conf=0.86)
- Partly supportedcites [234] Hoffmann, M. et al. SARS-CoV-2 variant B.1.617 is resistant to bamlanivimab and evades antibodies induced by infection and vaccination. Cell Rep. 36, 109415 (2021). sourceExperimental — accuracy not yet measured
The Results section ('Diminished neutralization by plasma from COVID-19 convalescent patients'; page unavailable) reports reduced neutralization of B.1.617 by plasma from 15 patients, averaging about 2-fold. It does not report that about 40% of samples had 3- to 10-fold reductions or that 15% had reductions greater than 10-fold. (LLM, conf=0.88)
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- Partly supported
None of the sources cited for this claim have been checked yet.
In the paper
“The Alpha variant is susceptible to neutralization by most neutralizing mAbs as well as by most plasma samples from previously infected persons 97,102,121,149,159,[203][204][205][206] (fIg.5).”
What the sources say
- Not checked yetcites [97] Chen, X. et al. Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab646 (2021). This paper presents a systematic review and meta-analysis of in vitro neutralization studies of SARS-CoV-2 variants by convalescent and vaccinee plasma. source
- Not checked yetcites [102] Supasa, P. et al. Reduced neutralization of SARS-CoV-2 B.1.1.7 variant by convalescent and vaccine sera. Cell 184, 2201–2211 (2021). source
- Not checked yetcites [121] Wang, P. et al. Antibody resistance of SARS-CoV-2 variants B.1.351 and B.1.1.7. Nature 593, 130–135 (2021). This paper presents a comprehensive analysis of the effects of Alpha and Beta variant mutations on antibody neutralization. source
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“The fact that the Alpha variant is rarely associated with reduced susceptibility to convalescent plasma is consistent with it not being associated with an increased risk of reinfection 207 .”
What the sources say
- Not checked yetcites [207] Graham, M. S. et al. Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study. Lancet Public Health 6, e335–e345 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“associated with increased transmissibility, increased risk of reinfection and/or reduced vaccine efficacy”
plaincorrelational- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“The Beta variant is associated with reduced susceptibility to many mAbs because E484K interferes with binding of several RBM class 1 and 2 mAbs and K417N interferes with the binding of several RBM class 1 mAbs 104,117,121,163,217 .”
What the sources say
- Not checked yetcites [104] Zhou, D. et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine induced sera. Cell 184, 2348–2361 (2021). source
- Not checked yetcites [117] Chen, R. E. et al. Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies. Nat. Med. 27, 717–726 (2021). source
- Not checked yetcites [121] Wang, P. et al. Antibody resistance of SARS-CoV-2 variants B.1.351 and B.1.1.7. Nature 593, 130–135 (2021). This paper presents a comprehensive analysis of the effects of Alpha and Beta variant mutations on antibody neutralization. source
plaindirect- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“E484K has resulted in 3-fold to 10-fold reduced susceptibility to about 30% and >10-fold reduced susceptibility to about 10% of convalescent plasma samples”
What the sources say
- Not checked yetcites [121] Wang, P. et al. Antibody resistance of SARS-CoV-2 variants B.1.351 and B.1.1.7. Nature 593, 130–135 (2021). This paper presents a comprehensive analysis of the effects of Alpha and Beta variant mutations on antibody neutralization. source
- Not checked yetcites [130] Greaney, A. J. et al. Complete mapping of mutations to the SARS-CoV-2 spike receptor-binding domain that escape antibody recognition. Cell Host Microbe 29, 44–57.e9 (2021). source
- Not checked yetcites [160] Liu, Z. et al. Identification of SARS-CoV-2 spike mutations that attenuate monoclonal and serum antibody neutralization. Cell Host Microbe 29, 477–488.e4 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“The Alpha variant also contains several non-spike mutations including nsp6:Δ106-108 and the nucleocapsid mutations D3L, R203K and G204R, which may increase transmission by antagonizing innate immunity 25,[185][186][187] .”
What the sources say
- Not checked yetcites [25] Martin, D. P. et al. The emergence and ongoing convergent evolution of the N501Y lineages coincides with a major global shift in the SARS-CoV-2 selective landscape. Preprint at medRxiv https://doi.org/10.1101/2021.02.23.21252268 (2021). source
- Not checked yetcites [185] Thorne, L. G. et al. Evolution of enhanced innate immune evasion by the SARS-CoV-2 B.1.1.7 UK variant. Preprint at bioRxiv https://doi.org/10.1101/2021.06.06.446826 (2021). This systems biology study shows that in contrast to earlier SARS-CoV-2 variants, the alpha variant may owe its increased transmissibility and virulence to its antagonism of cellular innate immunity. source
- Not checked yetcites [186] Jiang, H. et al. SARS-CoV-2 Orf9b suppresses type I interferon responses by targeting TOM70. Cell Mol. Immunol. 17, 998–1000 (2020). source
hedgedconditional- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
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In the paper
“N501Y increases ACE2 affinity 128,146,147 and increases virus replication in human upper-airway cells and in the upper respiratory tracts of hamsters 127”
What the sources say
- Not checked yetcites [128] Starr, T. N. et al. Deep mutational scanning of SARS-CoV-2 receptor binding domain reveals constraints on folding and ACE2 binding. Cell 182, 1295–1310.e20 (2020). source
- Not checked yetcites [146] Zhu, X. et al. Cryo-electron microscopy structures of the N501Y SARS-CoV-2 spike protein in complex with ACE2 and 2 potent neutralizing antibodies. PLoS Biol. 19, e3001237 (2021).
- Not checked yetcites [127] Liu, Y. et al. The N501Y spike substitution enhances SARS-CoV-2 transmission. Preprint at bioRxiv https://doi.org/10.1101/2021.03.08.434499 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“In the previously cited Qatar cohort study, the efficacy of BNT162b against the Beta variant was estimated to be 72%, which was 15% lower than that for the Alpha variant 211 .”
What the sources say
- Not checked yetcites [211] Abu-Raddad, L. J., Chemaitelly, H. & Butt, A. A. Effectiveness of the BNT162b2 Covid-19 Vaccine against the B.1.1.7 and B.1.351 Variants. N. Engl. J. Med. 385, 187-189 (2021). source
hedged- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Even though E484Q is more likely than T478K to evade antibody neutralization 48,100,165 , only the Delta variant has demonstrated increased transmissibility, spreading to 54 countries and rapidly replacing the Alpha variant in the UK 32,35 and the USA 33 .”
What the sources say
- Not checked yetcites [48] Weisblum, Y. et al. Escape from neutralizing antibodies by SARS-CoV-2 spike protein variants. eLife 9, e61312 (2020). source
- Not checked yetcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). source
- Not checked yetcites [165] Ferreira, I. et al. SARS-CoV-2 B.1.617 mutations L452 and E484Q are not synergistic for antibody evasion. J. Infect. Dis. https://doi.org/10.1093/infdis/jiab368 (2021). source
boosteddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“It also contains five NTD mutations, of which L18F has been shown to interfere with the binding of NTD-targeting neutralizing antibodies 51 .”
What the sources say
- Not checked yetcites [51] McCallum, M. et al. N-terminal domain antigenic mapping reveals a site of vulnerability for SARS-CoV-2. Cell 184, 2332–2347.e16 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“It was estimated to result in virus levels 3-4 times higher than earlier variants and to be responsible for an estimated 1.1-fold to 1.8-fold higher mortality 19 .”
What the sources say
- Not checked yetcites [19] Faria, N. R. et al. Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil. Science 372, 815–821 (2021). This paper presents an analysis showing that the Gamma variant is about twofold more transmissible than previous variants in Manaus, Brazil, and that it poses an increased risk of reinfection compared with previous variants. source
hedgeddirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Of the five FDA EUA-approved mAbs, bamlanivimab, etesevimab and casirivimab are largely inactive against B.1.351whereas imdevimab and sotrovimab, which bind to the RBD core, retain neutralizing activity 104,109,117,175,204 (TABLe 1).”
What the sources say
- Not checked yetcites [104] Zhou, D. et al. Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine induced sera. Cell 184, 2348–2361 (2021). source
- Not checked yetcites [109] Copin, R. et al. The monoclonal antibody combination REGEN-COV protects against SARS-CoV-2 mutational escape in preclinical and human studies. Cell 184, 3949–3961 (2021). source
- Not checked yetcites [117] Chen, R. E. et al. Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies. Nat. Med. 27, 717–726 (2021). source
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Of convalescent plasma samples, about 40% display 3-fold to 10-fold and 10% display >10-fold reduced Iota variant neutralizing activity 166,235 .”
What the sources say
- Not checked yetcites [166] Zhang, L. et al. Comparison of 10 emerging SARS-CoV-2 variants: infectivity, animal tropism, and antibody neutralization. Preprint at Research Square https://doi.org/10.21203/rs.3.rs-492659/v1 (2021). source
- Not checked yetcites [235] Zhou, H. et al. B.1.526 SARS-CoV-2 variants identified in new york city are neutralized by vaccine-elicited and therapeutic monoclonal antibodies. mBio https://doi.org/10.1128/mBio.01386-21 (2021). source
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Although SARS-CoV-2 variants differ in their transmission rates, disease severity and risk of reinfection, there is no evidence that they are differentially affected by non-pharmaceutical public health measures such as social distancing and the use of personal protective equipment, or that they will respond differently to most antiviral therapies.”
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“The Zeta variant was common in Brazil in late 2020 and early 2021 (ref. 157 ), but appears to be decreasing in prevalence.”
What the sources say
- Not checked yetcites [157] Ferrareze, P. A. G. et al. E484K as an innovative phylogenetic event for viral evolution: genomic analysis of the E484K spike mutation in SARS-CoV-2 lineages from Brazil. Infect. Genet. Evol. 93, 104941 (2021). source
hedged- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The two most recently approved mAb preparations, casirivimab/imdevimab and sotrovimab, retain activity against all VOCs and VOIs, in part because imdevimab and sotrovimab target the RBD core whereas the most prevalent immune escape mutations are in the RBD RBM.”
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“The Theta variant was first reported in March 2021 in the Philippines.It contains 13 lineage-defining mutations including N501Y, E484K, P681H and the NTD deletion at positions 141-143 (refs 155,156 ).”
What the sources say
- Not checked yetcites [155] Bascos, N. A. D., Mirano-Bascos, D. & Saloma, C. P. Structural analysis of spike protein mutations in an emergent SARS-CoV-2 variant from the Philippines. Preprint at bioRxiv https://doi.org/10.1101/2021.03.06.434059 (2021). source
- Not checked yetcites [156] Tablizo, F. A. et al. Genome sequencing and analysis of an emergent SARS-CoV-2 variant characterized by multiple spike protein mutations detected from the Central Visayas Region of the Philippines. Preprint at bioRxiv https://doi.org/10.1101/2021.03.03.21252812 (2021). source
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Of plasma samples from recipients of an mRNA vaccine, approximately 55% had 3-fold to 10-fold and 5% had >10-fold reduced neutralizing activity 100,118,122,234 .”
What the sources say
- Not checked yetcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). source
- Not checked yetcites [118] Liu, J. et al. BNT162b2-elicited neutralization of B.1.617 and other SARS-CoV-2 variants. Nature 596, 273–275 (2021). source
- Not checked yetcites [122] Edara, V. V. et al. Infection and Vaccine-Induced Neutralizing-Antibody Responses to the SARS-CoV-2 B.1.617 Variants. N. Engl. J. Med. 385, 664–666 (2021) source
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
In the paper
“The Iota variant was first identified in New York state.In June 2021, it had a prevalence of 5-10% in the USA but remained rare outside the USA 154 .”
What the sources say
- Not checked yetcites [154] Annavajhala, M. K. et al. A novel SARS-CoV-2 variant of concern, B.1.526, identified in New York. Preprint at bioRxiv https://doi.org/10.1101/2021.02.23.21252259 (2021). source
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The Beta and Gamma variants are each associated with increased transmissibility because of their ability to evade humoral immunity and cause reinfections.”
plaincorrelational- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“AY.1 and AY.2 are recently reported sub-lineages of the Delta variant that have developed additional mutations including the RBD mutation K417N (ref. 196 ).”
What the sources say
- Not checked yetcites [196] Mullen, J. L. et al. Outbreak.info https://outbreak.info/citation (2020).
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“It is highly prevalent in several South American countries and is associated with reduced susceptibility to the locally used CoronaVac vaccine 238 .”
What the sources say
- Not checked yetcites [238] Acevedo, M. L. et al. Infectivity and immune escape of the new SARS-CoV-2 variant of interest Lambda. Preprint at medRxiv https://doi.org/10.1101/2021.06.28.21259673 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“In case-control studies from the UK, the BNT162b vaccine was approximately 85% effective for the Delta variant whereas the AZD1222 vaccine was approximately 60% effective 232,233 .”
What the sources say
- Not checked yetcites [232] Bernal, J. L. et al. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant. N. Engl. J. Med. 385, 585–594 (2021). source
- Not checked yetcites [233] Sheikh, A., McMenamin, J., Taylor, B. & Robertson, C. SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet 397, 2461–2462 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“It was estimated to be about 20% more transmissible than co-circulating lineages and to be associated with twofold higher upper-airway virus levels 123,192 .”
What the sources say
- Not checked yetcites [123] Deng, X. et al. Transmission, infectivity, and neutralization of a spike L452R SARS-CoV-2 variant. Cell 184, 3426–3437.e8 (2021). source
- Not checked yetcites [192] Peng, J. et al. Estimation of secondary household attack rates for emergent spike L452R SARS-CoV-2 variants detected by genomic surveillance at a community-based testing site in San Francisco. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab283 (2021). source
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“The levels of neutralizing mAbs elicited by the mRNA vaccines has been high and in most persons are likely to be maintained for many months above the levels required for protection against even the most resistant circulating variants 164,239,240 .”
What the sources say
- Not checked yetcites [164] Greaney, A. J. et al. Antibodies elicited by mRNA-1273 vaccination bind more broadly to the receptor binding domain than do those from SARS-CoV-2 infection. Sci. Transl Med. 13, eabi9915 (2021). source
- Not checked yetcites [239] Wang, Z. et al. Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection. Nature 595, 426–431 (2021). source
- Not checked yetcites [240] Turner, J. S. et al. SARS-CoV-2 mRNA vaccines induce persistent human germinal centre responses. Nature https://doi.org/10.1038/s41586-021-03738-2 (2021). source
hedgeddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“The Eta variant is present at low levels in many countries, with Nigeria having the highest proportion of infections 236 .”
What the sources say
- Not checked yetcites [236] Ozer, E. A. et al. High prevalence of SARS-CoV-2 B.1.1.7 (UK variant) and the novel B.1.525 lineage in Oyo State, Nigeria. Preprint at medRxiv https://doi.org/10.1101/2021.04.09.21255206 (2021). source
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“It results in approximately 3-fold to 10-fold reduced susceptibility to 45% and >10-fold reduced susceptibility to 5% of convalescent plasma samples 100,118,214,215,231 (fIg.5).”
What the sources say
- Not checked yetcites [100] Liu, C. et al. Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum. Cell 184, 4220–4336 (2021). source
- Not checked yetcites [118] Liu, J. et al. BNT162b2-elicited neutralization of B.1.617 and other SARS-CoV-2 variants. Nature 596, 273–275 (2021). source
- Not checked yetcites [214] Planas, D. et al. Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization. Nature 596, 276–280 (2021). source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The Alpha and Delta variants are each associated with increased transmissibility and greater disease severity because of immune evasion, and potentially because of higher virus levels resulting from the antagonism of innate immunity.”
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
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- Based: unclear — It is unclear why the paper says it holds.
It may state two separate claims as one.
In the paper
“This paper presents a meta-analysis showing that the level of neutralizing antibodies elicited by a vaccine is strongly correlated with its efficacy.”
What the sources say
- Not checked yetcites Khoury, D. S. et al.
boostedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“This post-hoc analysis of a clinical trial shows that the beta variant was frequently responsible for reinfections in South Africa.”
What the sources say
- Not checked yetcites Shinde, V. et al.
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“This study demonstrates the likely importance of SARS-CoV-2 neutralizing mAb Fc-effector functions in an animal model.”
What the sources say
- Not checked yetcites Schäfer, A. et al.
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“This post-hoc analysis of a clinical trial shows that AZD1222 appeared ineffective at preventing infection with the beta variant.”
What the sources say
- Not checked yetcites Madhi, S. A. et al.
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“This experimental study shows that the plasma from persons infected with the beta variant can usually neutralize pre-variant viruses.”
What the sources say
- Not checked yetcites Moyo-Gwete, T. et al.
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“This systems biology study shows that in contrast to earlier SARS-CoV-2 variants, the alpha variant may owe its increased transmissibility and virulence to its antagonism of cellular innate immunity.”
What the sources say
- Not checked yetcites Thorne, L. G. et al.
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“This paper demonstrates that a high proportion of neutralizing antibodies elicited by SARS-CoV-2 infection will bind poorly to epitopes containing the spike RBD mutation E484K.”
What the sources say
- Not checked yetcites Greaney, A. J. et al.
boostedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
In the citing paper
“These VOCs exhibit increased transmissibility and/or immune evasion, traits that have been linked to mutations in the viral spike (S) protein”
From The Omicron variant is highly resistant against antibody-mediated neutralization: Implications for control of the COVID-19 pandemic (2022) · cites this paper as Tao et al., 2021
Citations
Cites
Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine
Polack, F. P., Thomas, S. J., Kitchin, N., Absalon, J., Gurtman, A., Lockhart, S., Perez, J. L., Pérez Marc, G., Moreira, E. D., Zerbini, C., et al. (2020) · New England Journal of Medicine · doi:10.1056/nejmoa2034577 · Cited by 14,592
Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine
Baden, L. R., El Sahly, H. M., Essink, B., Kotloff, K., Frey, S., Novak, R., Diemert, D., Spector, S. A., Rouphael, N., Creech, C. B., et al. (2021) · New England Journal of Medicine · doi:10.1056/nejmoa2035389 · Cited by 10,119
Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation
Wrapp, D., Wang, N., Corbett, K. S., Goldsmith, J. A., Hsieh, C.-L., Abiona, O., Graham, B. S., & McLellan, J. S. (2020) · Science · doi:10.1126/science.abb2507 · Cited by 8,897
Structure, function and antigenicity of the SARS-CoV-2 spike glycoprotein
Walls, A. C., Park, Y.-J., Tortorici, M. A., Wall, A., McGuire, A. T., & Veesler, D. (2020) · doi:10.1101/2020.02.19.956581 · Cited by 8,586
Structure of the SARS-CoV-2 spike receptor-binding domain bound to the ACE2 receptor
Lan, J., Ge, J., Yu, J., Shan, S., Zhou, H., Fan, S., Zhang, Q., Shi, X., Wang, Q., Zhang, L., et al. (2020) · Nature · doi:10.1038/s41586-020-2180-5 · Cited by 5,983
Voysey, M., Clemens, S. A. C., Madhi, S. A., Weckx, L. Y., Folegatti, P. M., Aley, P. K., Angus, B., Baillie, V. L., Barnabas, S. L., Bhorat, Q. E., et al. (2021) · The Lancet · doi:10.1016/s0140-6736(20)32661-1 · Cited by 4,616
Korber, B., Fischer, W. M., Gnanakaran, S., Yoon, H., Theiler, J., Abfalterer, W., Hengartner, N., Giorgi, E. E., Bhattacharya, T., Foley, B., et al. (2020) · Cell · doi:10.1016/j.cell.2020.06.043 · Cited by 4,281
Khoury, D. S., Cromer, D., Reynaldi, A., Schlub, T. E., Wheatley, A. K., Juno, J. A., Subbarao, K., Kent, S. J., Triccas, J. A., & Davenport, M. P. (2021) · Nature Medicine · doi:10.1038/s41591-021-01377-8 · Cited by 3,742
Structural basis of receptor recognition by SARS-CoV-2
Shang, J., Ye, G., Shi, K., Wan, Y., Luo, C., Aihara, H., Geng, Q., Auerbach, A., & Li, F. (2020) · Nature · doi:10.1038/s41586-020-2179-y · Cited by 3,661
SARS-CoV-2 variants, spike mutations and immune escape
Harvey, W. T., Carabelli, A. M., Jackson, B., Gupta, R. K., Thomson, E. C., Harrison, E. M., Ludden, C., Reeve, R., Rambaut, A., COVID-19 Genomics UK (COG-UK) Consortium, et al. (2021) · Nature Reviews Microbiology · doi:10.1038/s41579-021-00573-0 · Cited by 3,528
Self-citation
Research works printed but not linked: 1
- Edara, V. V., Hudson, W. H., Xie, X., Ahmed, R. & Suthar, M. S. Neutralizing antibodies against SARS-CoV-2 variants after infection and vaccination. JAMA 325, 1896–1898 (2021). · DOI · Paper page
Cited by
Sorted by citations
Cele, S., Jackson, L., Khoury, D. S., Khan, K., Moyo-Gwete, T., Tegally, H., San, J. E., Cromer, D., Scheepers, C., Amoako, D., et al. (2021) · doi:10.1101/2021.12.08.21267417 · Cited by 1,333
Markov, P. V., Ghafari, M., Beer, M., Lythgoe, K., Simmonds, P., Stilianakis, N. I., & Katzourakis, A. (2023) · Nature Reviews Microbiology · doi:10.1038/s41579-023-00878-2 · Cited by 1,179
Hoffmann, M., Krüger, N., Schulz, S., Cossmann, A., Rocha, C., Kempf, A., Nehlmeier, I., Graichen, L., Moldenhauer, A.-S., Winkler, M. S., et al. (2022) · Cell · doi:10.1016/j.cell.2021.12.032 · Cited by 889
“These VOCs exhibit increased transmissibility and/or immune evasion, traits that have been linked to mutations in the viral spike (S) protein (Harvey et al., 2021b; Tao et al., 2021).”
InfluentialCRISPR/Cas9 therapeutics: progress and prospects
Li, T., Yang, Y., Qi, H., Cui, W., Zhang, L., Fu, X., He, X., Liu, M., Li, P., & Yu, T. (2023) · Signal Transduction and Targeted Therapy · doi:10.1038/s41392-023-01309-7 · Cited by 824
Shifting mutational constraints in the SARS-CoV-2 receptor-binding domain during viral evolution
Starr, T. N., Greaney, A. J., Hannon, W. W., Loes, A. N., Hauser, K., Dillen, J. R., Ferri, E., Farrell, A. G., Dadonaite, B., McCallum, M., et al. (2022) · Science · doi:10.1126/science.abo7896 · Cited by 298
“Main text The SARS-CoV-2 spike receptor-binding domain (RBD) has undergone rapid evolution since the virus’s emergence (1).”
Background
Metadata
- Authors
- Tao, K., Tzou, P. L., Nouhin, J., Gupta, R. K., de Oliveira, T., Kosakovsky Pond, S. L., Fera, D., & Shafer, R. W.
- Affiliations
- Stanford Medicine (US)
- University of Cambridge (GB)
- Swarthmore College (US)
- Corresponding author
- Shafer, Robert W.
- Venue
- Nature Reviews Genetics
- Published
- 2021-09-17
- Volume
- 22
- Issue
- 12
- Pages
- 757-773
- ISSN
- 1471-0056 (ISSN-L)
- 1471-0064
- PMC
- PMC8447121
- OpenAlex
- W3199849883
- Cited by
- 1,009
- References
- 281
- Citations by year
- 2026: 43 · 2025: 90 · 2024: 170 · 2023: 251 · 2022: 415 · 2021: 38
- FWCI
- 25.63
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Locations
- Nature Reviews Genetics (publishedVersion, cc-by)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Works - Scholarship, Research, & Creative Expression (Swarthmore College) (submittedVersion)
- Funders
- University of Washington
- National Institute of Allergy and Infectious Diseases (R24AI136618)
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Keywords
- SARS-CoV-2, COVID-19 variants of concern, spike protein mutations, Alpha variant, Beta variant, Gamma variant, Delta variant, virus transmission, reinfection risk, neutralizing antibodies, vaccine effectiveness, herd immunity, viral replication fitness
- MeSH terms
- COVID-19, SARS-CoV-2, Epitopes, Biological Evolution, Humans, Mutation, Spike Glycoprotein, Coronavirus
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-06, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-10-06 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Cited sources are checked with a language model’s help (gpt-6-sol).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
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