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Cited by 228SARS-CoV-2 and COVID-19 ResearchCOVID-19 epidemiological studiesCOVID-19 Clinical Research Studies

Duration of mRNA vaccine protection against SARS-CoV-2 Omicron BA.1 and BA.2 subvariants in Qatar

Open access
Chemaitelly, Hiam, Ayoub, Houssein H., AlMukdad, Sawsan, Coyle, Peter, Tang, Patrick, Yassine, Hadi M., Al-Khatib, Hebah A., Smatti, Maria K. +16 more·2022·Nature Communications
DOI 10.1038/s41467-022-30895-3PMC PMC9163167

Published version of a preprint

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Abstract

SARS-CoV-2 Omicron BA.1 and BA.2 subvariants are genetically divergent. We conducted a matched, test-negative, case-control study to estimate duration of protection of the second and third/booster doses of mRNA COVID-19 vaccines against BA.1 and BA.2 infections in Qatar. BNT162b2 effectiveness was highest at 46.6% (95% CI: 33.4–57.2%) against symptomatic BA.1 and at 51.7% (95% CI: 43.2–58.9%) against symptomatic BA.2 infections in the first three months after the second dose, but declined to ~10% or below thereafter. Effectiveness rebounded to 59.9% (95% CI: 51.2–67.0%) and 43.7% (95% CI: 36.5–50.0%), respectively, in the first month after the booster dose, before declining again. Effectiveness against COVID-19 hospitalization and death was 70–80% after the second dose and >90% after the booster dose. mRNA-1273 vaccine protection showed similar patterns. mRNA vaccines provide comparable, moderate, and short-lived protection against symptomatic BA.1 and BA.2 Omicron infections, but strong and durable protection against COVID-19 hospitalization and death.

AI snapshot

Written from the paper’s full text.

TL;DR

In a matched, test-negative, case-control study in Qatar, mRNA vaccine effectiveness against symptomatic Omicron BA.1 and BA.2 infection was moderate (~50%) soon after the second dose, waned to ~10% or below by 4–6 months, rebounded after a booster, and then waned again. Protection against severe, critical, or fatal COVID-19 remained 70–80% after the second dose and >90% after BNT162b2 booster vaccination.

Key findings

  • BNT162b2 effectiveness against symptomatic BA.1 infection was 46.6% (95% CI: 33.4–57.2%) in the first 3 months after dose 2 and against symptomatic BA.2 was 51.7% (95% CI: 43.2–58.9%), declining to ~10% or below thereafter; after booster, effectiveness was 59.9% (95% CI: 51.2–67.0%) for BA.1 and 43.7% (95% CI: 36.5–50.0%) for BA.2 in the first month.
  • For any symptomatic Omicron infection, BNT162b2 effectiveness was 47.8% (95% CI: 40.8–53.9%) 1–3 months after dose 2, rebounded to 55.5% (95% CI: 49.3–61.0%) 2–3 weeks after booster, and declined to 21.9% (95% CI: 7.7–33.9%) from week 14 onward.
  • mRNA-1273 showed similar patterns; for example, effectiveness against symptomatic BA.1 was 71.0% (95% CI: 24.0–89.0%) 1–3 months after dose 2 and 51.5% (95% CI: 32.3–65.2%) <1 month after booster, while BA.2 estimates were lower and less precise.
  • Effectiveness against any severe, critical, or fatal COVID-19 due to Omicron was 70–80% at any time after the second dose for both vaccines; BNT162b2 effectiveness after booster was >90% (90.9%, 95% CI: 78.6–96.1% at 1–6 weeks; 90.1%, 95% CI: 80.6–95.0% at ≥7 weeks).

Methods

  • Matched, test-negative, case-control study using national Qatar SARS-CoV-2 databases, conducted December 23, 2021–February 28, 2022, with the any-symptomatic-Omicron booster analysis extended to April 11, 2022.
  • Cases were symptomatic PCR-positive persons and controls were PCR-negative persons, exact-matched by sex, 10-year age group, nationality, and calendar week of PCR test; conditional logistic regression estimated vaccine effectiveness.
  • BA.1 and BA.2 were proxied by S-gene target failure (SGTF) versus non-SGTF using the TaqPath PCR assay; severity, criticality, and fatality were classified per WHO guidelines. By February 28, 2022, 1,308,926 individuals had received ≥2 BNT162b2 doses (355,979 boosted) and 894,142 had received ≥2 mRNA-1273 doses (146,961 boosted).

Limitations

  • The paper states that case numbers were insufficient to estimate duration of protection against hospitalization and death separately for BA.1 and BA.2; subvariant ascertainment relied on proxy SGTF criteria; protection was assessed only several months after dose 2 and several weeks after booster, so longer-term protection remains uncertain.
  • The paper also states that negative effectiveness estimates at ≥7 months after dose 2 likely reflect bias rather than true negative biological effectiveness, possibly from behavioral differences or an unvaccinated reference group composed mainly of children/young persons who may not be immune-naïve; matching for comorbidities was not possible.
  • The paper notes possible residual bias from observational design, test-seeking behavior, rapid-antigen testing expansion, and limited generalizability because only 9% of Qatar’s population is ≥50 years old.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41467-022-30895-3

Cites

Statistics

Nothing to recompute.

Claims the paper makes

0 of 73 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    BNT162b2 effectiveness against symptomatic BA.1 infection was 46.6% (95% CI 33.4-57.2%) in the first 3 months after the second dose.

    “BNT162b2 effectiveness against symptomatic BA.1 infection was highest at 46.6% (95% confidence interval (CI): 33.4–57.2%) in the first 3 months after the second dose”
    • Also stated in: § Main analyses · plain
      “1–3 months after Dose 2 and no Dose 3 | 130 | 1992 | 376 | 3409 | 46.6 (33.4 to 57.2)”
    Quote in the paperSubstantial claim
  • Findingown data

    BNT162b2 effectiveness against symptomatic BA.1 infection was 59.9% (95% CI 51.2-67.0%) in the first month after the booster dose.

    “Effectiveness rapidly rebounded to 59.9% (95% CI: 51.2–67.0%) in the first month after the booster dose”
    • Also stated in: § Main analyses · plain
      “<1 month after Dose 3 | 180 | 2008 | 622 | 3339 | 59.9 (51.2 to 67.0)”
    Quote in the paperSubstantial claim
  • Findingown data

    BNT162b2 effectiveness against symptomatic BA.1 infection was 40.5% (95% CI 30.8-48.8%) in the second month after the booster dose and thereafter.

    “but then declined to 40.5% (95% CI: 30.8–48.8%) in the second month and thereafter.”
    • Also stated in: § Main analyses · plain
      “≥1 month after Dose 3 | 483 | 2031 | 1145 | 3441 | 40.5 (30.8 to 48.8)”
    Quote in the paperSubstantial claim
  • Findingown data

    BNT162b2 effectiveness against symptomatic BA.1 infection declined to ~10% or below after the first 3 months after the second dose.

    “BNT162b2 effectiveness against symptomatic BA.1 infection was highest at 46.6% (95% confidence interval (CI): 33.4–57.2%) in the first 3 months after the second dose, but then declined to ~10% or below thereafter (Fig. 3a and Table 3).”
    Quote in the paperSubstantial claim
  • Findingown data

    Vaccine effectiveness reached small but statistically significant negative values at 7 months or more after the second dose.

    “Vaccine effectiveness reached small but statistically significant negative values at 7 months or more after the second dose.”
    Quote in the paperSubstantial claim
  • May combine two claims. 24
  • The quote only partly states this claim. 1
  • Classified as probably not a substantial claim. 8

  • May combine two claims.

    Findingown data

    In Qatar's Omicron wave, BA.1 first dominated, but within a few days BA.2 predominated.

    “The wave was first dominated by the BA.1 Omicron subvariant, but within a few days, the BA.2 subvariant predominated (Fig. 1).”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    mRNA-1273 vaccine protection showed similar patterns to BNT162b2 for symptomatic BA.1 and BA.2 Omicron infections.

    “mRNA-1273 vaccine protection showed similar patterns.”
    • Also stated in: § Main analyses · plain
      “A similar pattern was observed for mRNA-1273 effectiveness (Fig. 3b and Table 4).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    For each of the BA.1 and BA.2 Omicron subvariants, mRNA vaccine effectiveness against symptomatic infection was approximately 50% in the first 3 months after the second dose.

    “For each of these subvariants, vaccine effectiveness against symptomatic infection was ~50% in the first 3 months after the second dose, but declined to negligible levels thereafter.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    For each of the BA.1 and BA.2 Omicron subvariants, mRNA vaccine effectiveness against symptomatic infection declined to negligible levels after the first 3 months following the second dose.

    “For each of these subvariants, vaccine effectiveness against symptomatic infection was ~50% in the first 3 months after the second dose, but declined to negligible levels thereafter.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Of 286 Omicron infections with confirmed subvariant status, 68 (23.8%) were BA.1 cases and 218 (76.2%) were BA.2 cases.

    “Of 286 Omicron infections with confirmed subvariant status, 68 (23.8%) were BA.1 cases and 218 (76.2%) were BA.2 cases.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    A total of 8811 random SARS-CoV-2-positive specimens collected between December 22, 2021 and February 28, 2022 were RT-qPCR genotyped, identifying 470 B.1.617.2-like Delta cases, 1017 BA.1-like Omicron cases, 4429 BA.2-like Omicron cases, and 2895 undetermined cases.

    “Additionally, a total of 8811 random SARS-CoV-2-positive specimens collected between December 22, 2021 and February 28, 2022 were RT-qPCR genotyped. The RT-qPCR genotyping identified 470 B.1.617.2-like Delta case, 1017 BA.1-like Omicron cases, 4429 BA.2-like Omicron cases, and 2895 were undetermined cases where the genotype could not be assigned due to weak PCR Ct values.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductcitation

    The method of ascertaining BA.1 and BA.2 using S-gene target failure (SGTF) with the TaqPath PCR assay is well established for Omicron subvariants and for other variants such as Alpha.

    “BA.1 and BA.2 ascertainment was based on proxy criteria, presence or absence of an S-gene “target failure” using the TaqPath PCR assay (Methods), but this method of ascertainment is well established not only for Omicron subvariants, but also for other variants such as Alpha27–29.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [27] UK Health Security Agency (UKHSA). SARS-CoV-2 variants of concern and variants under investigation in England: Technical briefing 34. Ref: UKHSA publications gateway number GOV-12276 (2022). Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1077180/Technical-Briefing-42-20May2022.pdf, Accessed on May 27, 2022. UKHSA: London.

      Not checked in the free run.

    • cites [28] Abu-Raddad, L. J. et al. Introduction and expansion of the SARS-CoV-2 B.1.1.7 variant and reinfections in Qatar: A nationally representative cohort study. Plos Med. 18, e1003879 (2021). source

      Not checked in the free run.

    • cites [29] 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 in the free run.

  • May combine two claims.

    Study design and conductnone given

    Vaccine protection was assessed for only several months after the second dose and only several weeks after the booster dose.

    “Vaccine protection was assessed for only several months after the second dose, and only several weeks after the booster dose.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductcitation

    Unvaccinated adults are a small minority that may not be truly immune-naïve due to undocumented prior SARS-CoV-2 infections.

    “Unvaccinated adults are a small minority that may not be truly immune-naïve due to undocumented prior SARS-CoV-2 infections, especially now that we are two years into this pandemic.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    mRNA vaccines provide comparable, moderate, and short-lived protection against symptomatic BA.1 and BA.2 Omicron infections, but strong and durable protection against COVID-19 hospitalization and death.

    “mRNA vaccines provide comparable, moderate, and short-lived protection against symptomatic BA.1 and BA.2 Omicron infections, but strong and durable protection against COVID-19 hospitalization and death.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductown data

    The 95% CIs around estimates of mRNA-1273 effectiveness against any severe, critical, or fatal COVID-19 after the booster dose lacked adequate statistical precision because there were too few hospitalized COVID-19 cases among mRNA-1273 vaccinated persons.

    “95% CIs around estimates of mRNA-1273 effectiveness against any severe, critical, or fatal COVID-19 after the booster dose lacked adequate statistical precision—there were too few hospitalized COVID-19 cases among mRNA-1273 vaccinated persons (Table 5).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The bias may have arisen from vaccinated persons having a higher social contact rate or adhering less to safety measures than unvaccinated persons.

    “This bias may have risen from vaccinated persons having a higher social contact rate or adhering less to safety measures than unvaccinated persons31–33.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [31] Makhoul, M. et al. Epidemiological impact of SARS-CoV-2 vaccination: mathematical modeling analyses. Vaccines 8, 668 (2020). source

      Not checked in the free run.

    • cites [32] Usherwood, T., LaJoie, Z. & Srivastava, V. A model and predictions for COVID-19 considering population behavior and vaccination. Sci. Rep. 11, 12051 (2021). source

      Not checked in the free run.

    • cites [33] Andersson, O., Campos-Mercade, P., Meier, A. N. & Wengström, E. Anticipation of COVID-19 vaccines reduces social distancing. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3765329. (SSRN, 2021). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    The vast majority of individuals were vaccinated in Qatar, but if vaccinated elsewhere, those vaccinations were still registered in the health system at the port of entry upon arrival in Qatar.

    “The vast majority of individuals were vaccinated in Qatar, but if vaccinated elsewhere, those vaccinations were still registered in the health system at the port of entry upon arrival in Qatar.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The large Omicron-wave exponential-growth phase in Qatar started on December 19, 2021 and peaked in mid-January, 2022.

    “The large Omicron-wave exponential-growth phase in Qatar started on December 19, 2021 and peaked in mid-January, 20222–5.”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [2] National Project of Surveillance for Variants of Concern and Viral Genome Sequencing. Qatar viral genome sequencing data. Data on randomly collected samples. https://www.gisaid.org/phylodynamics/global/nextstrain/. Accessed 6 Feb 2022. (2022).

      Not checked in the free run.

    • cites [3] Altarawneh, H. N. et al. Protection against the Omicron variant from previous SARS-CoV-2 infection. N. Engl. J. Med. 386, 1288–1290 (2022). source

      Not checked in the free run.

    • cites [4] Chemaitelly, H. et al. Protection of Omicron sub-lineage infection against reinfection with another Omicron sub-lineage. medRxiv https://doi.org/10.1101/2022.02.24.22271440 (2022). source

      Not checked in the free run.

    • cites [5] Abu-Raddad, L. J. et al. Effect of mRNA vaccine boosters against SARS-CoV-2 Omicron infection in Qatar. N. Engl J. Med. 386, 1804–1816 (2022). source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductnone given

    COVID-19 laboratory testing, vaccination, clinical infection data, and demographic details were extracted from national, federated SARS-CoV-2 databases that include, with no missing information, all PCR testing, COVID-19 vaccinations, and COVID-19 hospitalizations and deaths in Qatar since the start of the pandemic.

    “COVID-19 laboratory testing, vaccination, clinical infection data, and demographic details were extracted from the national, federated SARS-CoV-2 databases that include, with no missing information, all polymerase chain reaction (PCR) testing, COVID-19 vaccinations, and COVID-19 hospitalizations and deaths in Qatar since the start of the pandemic.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Study design and conductreasoning

    Rapid-antigen testing (RAT) was broadly implemented in the population and probably did not differentially affect PCR testing to introduce bias.

    “However, RAT was broadly implemented in the population and probably did not differentially affect PCR testing to introduce bias.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductcitation

    Classification of COVID-19 case severity, criticality, and fatality followed World Health Organization (WHO) guidelines, and assessments were made by trained medical personnel using individual chart reviews.

    “Classification of COVID-19 case severity (acute-care hospitalizations)9, criticality (intensive-care-unit hospitalizations)9, and fatality10 followed World Health Organization (WHO) guidelines, and assessments were made by trained medical personnel using individual chart reviews (detailed description below).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [9] World Health Organization. COVID-19 clinical management: living guidance. Available from: https://www.who.int/publications-detail-redirect/WHO-2019-nCoV-clinical-2021-2. Accessed 3 Mar 2022. (2022).

      Not checked in the free run.

    • cites [10] World Health Organization. International guidelines for certification and classification (coding) of COVID-19 as cause of death. https://www.paho.org/en/documents/international-guidelines-certification-and-classification-coding-covid-19-cause-death. Document Number: WHO/HQ/DDI/DNA/CAT. Accessed 3 Mar 2022. (2022).

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Qatar has young, international demographics: only 9% of the population is aged 50 years or older and 89% are international expatriates from over 150 countries.

    “Qatar has young, international demographics. Only 9% of Qatar’s population is ≥50 years of age and 89% are international expatriates from over 150 countries15,41.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [15] Abu-Raddad, L. J. et al. Characterizing the Qatar advanced-phase SARS-CoV-2 epidemic. Sci. Rep. 11, 6233 (2021). source

      Not checked in the free run.

    • cites [41] Planning and Statistics Authority-State of Qatar. Qatar Monthly Statistics. https://www.psa.gov.qa/en/pages/default.aspx. Accessed 26 May 2020. (2020).

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The study was reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

    “The study was reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Study design and conductnone given

    One cannot exclude the possibility that in real-world data, bias could arise in unexpected ways or from unknown sources.

    “Nonetheless, one cannot exclude the possibility that in real-world data, bias could arise in unexpected ways, or from unknown sources, such as subtle differences in test-seeking behavior or changes in the pattern of testing with introduction of other testing modalities, such as rapid-antigen testing (RAT).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Vaccine protection against COVID-19 hospitalization and death is strong and durable after the second dose, and is most robust after a booster dose.

    “Meanwhile, vaccine protection against COVID-19 hospitalization and death is strong and durable after the second dose, and is most robust after a booster dose.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Consistent findings were reached, indicating rapid waning of vaccine protection against symptomatic Omicron infection, consistent with findings of other studies for effectiveness against Omicron infection (with no BA.1/BA.2 subvariant specified).

    “Notwithstanding these limitations, consistent findings were reached, indicating rapid waning of vaccine protection against symptomatic Omicron infection that are consistent with findings of other studies for effectiveness against Omicron infection (with no BA.1/BA.2 subvariant specified)42–48.”
    Quote in the paperNot a substantial claim0 of 7 sources checked
    • cites [42] Andrews, N. et al. Covid-19 vaccine effectiveness against the Omicron (B.1.1.529) variant. N. Engl. J. Med. 386, 1532–1546 (2022). source

      Not checked in the free run.

    • cites [43] Buchan, S. A. et al. Effectiveness of COVID-19 vaccines against Omicron or Delta infection. medRxiv https://doi.org/10.1101/2021.12.30.21268565 (2022). source

      Not checked in the free run.

    • cites [44] Hansen, C. H. et al. Vaccine effectiveness against SARS-CoV-2 infection with the Omicron or Delta variants following a two-dose or booster BNT162b2 or mRNA-1273 vaccination series: a Danish cohort study. medRxiv https://doi.org/10.1101/2021.12.20.21267966 (2021). source

      Not checked in the free run.

    • cites [45] Patalon, T. et al. Waning effectiveness of the third dose of the BNT162b2 mRNA COVID-19 vaccine. medRxiv https://doi.org/10.1101/2022.02.25.22271494 (2022). source

      Not checked in the free run.

    • cites [46] Šmíd, M. et al. Protection by vaccines and previous infection against the Omicron variant of SARS-CoV-2. medRxiv https://doi.org/10.1101/2022.02.24.22271396 (2022). source

      Not checked in the free run.

    • cites [47] Tseng, H. F. et al. Effectiveness of mRNA-1273 against SARS-CoV-2 Omicron and Delta variants. Nat. Med. 28, 1063–1071 (2022). source

      Not checked in the free run.

    • cites [48] Powell, A. A. et al. Effectiveness of BNT162b2 against COVID-19 in adolescents. Lancet Infect. Dis. 22, 581–583 (2022). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    The study was approved by the Hamad Medical Corporation and Weill Cornell Medicine-Qatar Institutional Review Boards with a waiver of informed consent.

    “Hamad Medical Corporation and Weill Cornell Medicine—Qatar Institutional Review Boards approved this retrospective study with waiver of informed consent.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductcitation

    Our recent study of the effectiveness of booster vaccination against any symptomatic Omicron infection, relative to the primary series, used a cohort study design and its results are consistent with results generated in the present study using the test-negative, case-control study design.

    “Moreover, our recent study of the effectiveness of booster vaccination against any symptomatic Omicron infection, relative to that of the primary series, used a cohort study design5 and its results are consistent with results generated in the present study using the test-negative, case–control study design.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] Abu-Raddad, L. J. et al. Effect of mRNA vaccine boosters against SARS-CoV-2 Omicron infection in Qatar. N. Engl J. Med. 386, 1804–1816 (2022). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Study design and conductcitation

    With the mass scale of PCR testing in Qatar, the likelihood of bias is perhaps minimized.

    “Moreover, with the mass scale of PCR testing in Qatar13, the likelihood of bias is perhaps minimized.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] Chemaitelly, H. et al. Waning of BNT162b2 vaccine protection against SARS-CoV-2 infection in Qatar. N. Engl. J. Med. 385, e83 (2021). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Cases and controls were exact-matched by sex, 10-year age group, nationality, and calendar week of PCR test.

    “Cases (BA.1, BA.2, or any-Omicron-subvariant infected persons) and controls (uninfected persons) were exact-matched by sex, 10-year age group, nationality, and calendar week of PCR test.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductown data

    The agreement between RT-qPCR genotyping and sequencing was 100% for Delta (n = 82), 100% for Omicron BA.1 (n = 18), and 100% for Omicron BA.2 (n = 29).

    “The agreement between RT-qPCR genotyping and sequencing was 100% for Delta (n = 82), 100% for Omicron BA.1 (n = 18), and 100% for Omicron BA.2 (n = 29).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductcitation

    Vaccine effectiveness against symptomatic SARS-CoV-2 Omicron infection during the Omicron wave in Qatar was estimated using the test-negative, case-control study design, a standard design for assessing vaccine effectiveness.

    “Vaccine effectiveness against symptomatic SARS-CoV-2 Omicron (B.1.1.529)1 infection during the large Omicron wave in Qatar, between December 23, 2021 and February 28, 2022, was estimated using the test-negative, case–control study design, a standard design for assessing vaccine effectiveness11,12,36,40.”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [11] Jackson, M. L. & Nelson, J. C. The test-negative design for estimating influenza vaccine effectiveness. Vaccine 31, 2165–2168 (2013). source

      Not checked in the free run.

    • cites [12] Verani, J. R. et al. Case-control vaccine effectiveness studies: preparation, design, and enrollment of cases and controls. Vaccine 35, 3295–3302 (2017). source

      Not checked in the free run.

    • cites [36] Chemaitelly, H. et al. mRNA-1273 COVID-19 vaccine effectiveness against the B.1.1.7 and B.1.351 variants and severe COVID-19 disease in Qatar. Nat. Med. 27, 1614–1621 (2021). source

      Not checked in the free run.

    • cites [40] Lopez Bernal, J. et al. Effectiveness of Covid-19 vaccines against the B.1.617.2 (Delta) variant. N. Engl. J. Med. 385, 585–594 (2021). source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    The study duration coincided with the intense Omicron wave where Delta incidence was limited.

    “The study duration coincided with the intense Omicron wave where Delta incidence was limited.”
    Quote in the paperSubstantial claim
29 of 29

  • The authors state this as an assumption.

    Any PCR-positive test during the study duration (December 23, 2021 to February 28, 2022) was an Omicron infection.

    “Accordingly, any PCR-positive test during the study duration, between December 23, 2021 and February 28, 2022, was assumed to be an Omicron infection.”
1 of 1

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?

  • Among 4 studies that compared VE against outcomes of SARS-CoV-2 infection and/or symptomatic COVID-19 disease between BA.1 and BA.2, all showed lower VE against BA.2.

    “Among 4 studies that compared VE against outcomes of SARS-CoV-2 infection and/or symptomatic COVID-19 disease between BA.1 and BA.2, all showed lower VE against BA.2 [26,29,31,33].”

    From Assessing COVID-19 vaccine effectiveness against Omicron subvariants: Report from a meeting of the World Health Organization (2023) · cites this paper as [29]

    The Discussion (page not provided) says there were no discernable differences in the duration of protection against BA.1 versus BA.2 symptomatic infection. The Results (page not provided) also report higher effectiveness against BA.2 than BA.1 in the first three months after a second BNT162b2 dose (51.7% versus 46.6%), contrary to an unqualified claim that this study showed lower effectiveness against BA.2. (LLM, conf=0.87)

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured

  • Eight studies assessed VE of primary series or first booster dose vaccination separately for at least two different Omicron subvariants (six assessed VE of both primary series and booster dose vaccination and two assessed VE of a booster dose only).

    “Eight studies assessed VE of primary series or first booster dose vaccination separately for at least two different Omicron subvariants (six assessed VE of both primary series and booster dose vaccination and two assessed VE of a booster dose only, Tables 1 and 2) [21,24-26,28-33].”

    From Assessing COVID-19 vaccine effectiveness against Omicron subvariants: Report from a meeting of the World Health Organization (2023) · cites this paper as [29]

  • Among 315 random SARS-CoV-2-positive specimens sequenced, 300 (95.2%) were omicron and 15 (4.8%) were delta.

    “Of these specimens, 300 (95.2%) were confirmed to be omicron infections and 15 (4.8%) to be delta (or B.1.617.2)1 infections.”

    From Effects of Previous Infection and Vaccination on Symptomatic Omicron Infections (2022) · cites this paper as [3]

  • Previous infections in the study were considered to be caused by variants other than omicron because they occurred before the omicron wave in Qatar.

    “Accordingly, previous infections in this study were considered to be due to variants other than omicron, since they occurred before the omicron wave in Qatar.”

    From Effects of Previous Infection and Vaccination on Symptomatic Omicron Infections (2022) · cites this paper as [3]

  • Most persons received their third dose less than 45 days earlier, which may explain the relatively high effectiveness.

    “However, most persons received their third dose less than 45 days earlier, perhaps explaining the relatively high effectiveness.3”

    From Effects of Previous Infection and Vaccination on Symptomatic Omicron Infections (2022) · cites this paper as [3]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • mRNA-1273 second-dose estimates fall outside the stated 70-80% range

    Minor

    The stated range is for both vaccines at any time after the second dose, but Table 5 reports mRNA-1273 effectiveness of 87.1% at 1-6 months and 68.4% at 7 months or later.

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References 52 · Cited by 228

Research works printed but not linked: 1

  1. Rothman, K. J., Greenland, S. & Lash, T. L. Modern epidemiology, 3rd edn. (Wolters Kluwer Health/Lippincott Williams & Wilkins, 2008).

Authors
Chemaitelly, H., Ayoub, H. H., AlMukdad, S., Coyle, P., Tang, P., Yassine, H. M., Al-Khatib, H. A., Smatti, M. K., Hasan, M. R., Al-Kanaani, Z., Al-Kuwari, E., Jeremijenko, A., Kaleeckal, A. H., Latif, A. N., Shaik, R. M., Abdul-Rahim, H. F., Nasrallah, G. K., Al-Kuwari, M. G., Butt, A. A., Al-Romaihi, H. E., Al-Thani, M. H., Al-Khal, A., Bertollini, R., & Abu-Raddad, L. J.
Affiliations
  • Cornell University (US)
  • Qatar University (QA)
  • Queen's University Belfast (GB)
  • Sidra Medical and Research Center (QA)
  • Hamad Medical Corporation (QA)
  • Ministry of Public Health (QA)
Corresponding author
  • Chemaitelly, Hiam
  • Abu-Raddad, Laith J.
ORCID
Venue
Nature Communications
Publisher
Springer Science and Business Media LLC
Published
2022-06-02
Volume
13
Issue
1
Pages
3082-3082
ISSN
2041-1723 (ISSN-L)
DOI
10.1038/s41467-022-30895-3
PMC
PMC9163167
OpenAlex
W4281827985
Cited by
228
References
52
Citations by year
2026: 8 · 2025: 15 · 2024: 25 · 2023: 89 · 2022: 91
FWCI
26.89
Type
journal article
Language
en
Open access
Licence
Locations
  • Nature Communications (publishedVersion, cc-by)
  • medRxiv (acceptedVersion)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Research Portal (Queen's University Belfast) (submittedVersion, cc-by)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • Qatar University QSpace (Qatar University) (submittedVersion)
Funders
  • Biomedical Research Program and the Biostatistics, Epidemiology, and Biomathematics Research Core, both at Weill Cornell Medicine-Qatar
  • Hamad Medical Corporation
  • Ministry of Public Health, Hamad Medical Corporation, and Sidra Medicine
  • Qatar Genome Programme and Qatar University Biomedical Research Center
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
  • Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
Keywords
SARS-CoV-2 Omicron BA.1, SARS-CoV-2 Omicron BA.2, COVID-19 mRNA vaccine, BNT162b2, mRNA-1273, vaccine effectiveness, duration of protection, booster vaccination, COVID-19 hospitalization, COVID-19 mortality, Qatar
MeSH terms
COVID-19, SARS-CoV-2, COVID-19 Vaccines, mRNA Vaccines, BNT162 Vaccine, 2019-nCoV Vaccine mRNA-1273, Humans, Qatar, Vaccines, Synthetic, Case-Control Studies

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