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Cited by 305SARS-CoV-2 and COVID-19 ResearchCOVID-19 epidemiological studiesCOVID-19 Clinical Research Studies

Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study

Open access
Graham, Mark S, Sudre, Carole H, May, Anna, Antonelli, Michela, Murray, Benjamin, Varsavsky, Thomas, Kläser, Kerstin, Canas, Liane S +606 more·2021·The Lancet Public Health
DOI 10.1016/s2468-2667(21)00055-4PMC PMC8041365
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Abstract

Background The SARS-CoV-2 variant B.1.1.7 was first identified in December, 2020, in England. We aimed to investigate whether increases in the proportion of infections with this variant are associated with differences in symptoms or disease course, reinfection rates, or transmissibility. Methods We did an ecological study to examine the association between the regional proportion of infections with the SARS-CoV-2 B.1.1.7 variant and reported symptoms, disease course, rates of reinfection, and transmissibility. Data on types and duration of symptoms were obtained from longitudinal reports from users of the COVID Symptom Study app who reported a positive test for COVID-19 between Sept 28 and Dec 27, 2020 (during which the prevalence of B.1.1.7 increased most notably in parts of the UK). From this dataset, we also estimated the frequency of possible reinfection, defined as the presence of two reported positive tests separated by more than 90 days with a period of reporting no symptoms for more than 7 days before the second positive test. The proportion of SARS-CoV-2 infections with the B.1.1.7 variant across the UK was estimated with use of genomic data from the COVID-19 Genomics UK Consortium and data from Public Health England on spike-gene target failure (a non-specific indicator of the B.1.1.7 variant) in community cases in England. We used linear regression to examine the association between reported symptoms and proportion of B.1.1.7. We assessed the Spearman correlation between the proportion of B.1.1.7 cases and number of reinfections over time, and between the number of positive tests and reinfections. We estimated incidence for B.1.1.7 and previous variants, and compared the effective reproduction number, R t , for the two incidence estimates. Findings From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36 920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up. We found no changes in reported symptoms or disease duration associated with B.1.1.7. For the same period, possible reinfections were identified in 249 (0·7% [95% CI 0·6–0·8]) of 36 509 app users who reported a positive swab test before Oct 1, 2020, but there was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants. Reinfection occurrences were more positively correlated with the overall regional rise in cases (Spearman correlation 0·56–0·69 for South East, London, and East of England) than with the regional increase in the proportion of infections with the B.1.1.7 variant (Spearman correlation 0·38–0·56 in the same regions), suggesting B.1.1.7 does not substantially alter the risk of reinfection. We found a multiplicative increase in the R t of B.1.1.7 by a factor of 1·35 (95% CI 1·02–1·69) relative to pre-existing variants. However, R t fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant. Interpretation The lack of change in symptoms identified in this study indicates that existing testing and surveillance infrastructure do not need to change specifically for the B.1.1.7 variant. In addition, given that there was no apparent increase in the reinfection rate, vaccines are likely to remain effective against the B.1.1.7 variant. Funding Zoe Global, Department of Health (UK), Wellcome Trust, Engineering and Physical Sciences Research Council (UK), National Institute for Health Research (UK), Medical Research Council (UK), Alzheimer's Society.

Verified 2026-10-06 · 1 reference not checked yet

AI snapshot

Written from the paper’s full text.

TL;DR

In this ecological study, increasing regional prevalence of SARS-CoV-2 variant B.1.1.7 was not associated with changes in self-reported symptoms or disease duration, nor with higher reinfection frequency. B.1.1.7 was associated with increased transmissibility, with a mean multiplicative increase in Rt of 1·35, but Rt fell below 1 during regional and national lockdowns even in areas with high B.1.1.7 prevalence.

Key findings

  • Among 36 920 COVID Symptom Study app users reporting positive COVID-19 tests between Sept 28 and Dec 27, 2020, there was no evidence of an association between the regional proportion of B.1.1.7 infections and reported symptoms, number of symptoms, asymptomatic infection, self-reported hospital visits, or long symptom duration after adjustment and false-discovery-rate control.
  • Possible reinfection was identified in 249 (0·7% [95% CI 0·6–0·8]) of 36 509 app users who reported a positive swab before Oct 1, 2020; reinfection frequency was not higher with B.1.1.7. Reinfection occurrences correlated more with overall regional rises in cases (Spearman correlation 0·56–0·69 for South East, London, and East of England) than with regional increases in B.1.1.7 proportion (0·38–0·56 in the same regions).
  • B.1.1.7 was associated with a mean multiplicative increase in Rt of 1·35 (95% CI 1·02–1·69) and a mean additive increase of 0·34 (95% CI 0·02–0·66) relative to pre-existing variants. After the second lockdown, the mean multiplicative increase was 1·28 (95% CI 1·02–1·61); using SGTF data after Dec 1, 2020, it was 1·25 (95% CI 1·17–1·34).
  • Rt fell to around 0·8 in London, the South East, and East of England during the national lockdown beginning Jan 5, 2021, where at least 80% of infections were likely due to B.1.1.7.

Methods

  • Ecological study combining longitudinal self-reported symptom and test data from the COVID Symptom Study app (1 767 914 UK users active Sept 28–Dec 27, 2020; symptom analyses focused on 36 920 positive-test users with known region and healthy at sign-up) with COG-UK genomic surveillance and Public Health England spike-gene target failure (SGTF) data.
  • Linear regression examined associations between regional B.1.1.7 proportion and reported symptoms, adjusted for age, sex, regional temperature, and humidity, with false discovery rate control. Possible reinfection was defined as two reported positive tests separated by more than 90 days with more than 7 symptom-free days before the second positive test; Spearman correlations and Mann-Whitney U tests compared reinfection correlations.
  • Incidence was decomposed into B.1.1.7 and pre-existing variant time-series using COG-UK proportions; Rt was estimated separately for each using a Poisson process and Markov Chain Monte-Carlo methods, assuming a gamma-distributed serial interval with α=6·0 and β=1·5, and compared when regional B.1.1.7 proportion exceeded 3%.

Limitations

  • The paper states that the ecological design cannot support causal interpretation, assumes all non-B.1.1.7 variants had the same symptoms, immune response, and transmissibility, and notes that undetected variants with different characteristics cannot be ruled out.
  • The paper states that participatory app data have demographic biases, possible ascertainment or collider bias, and self-report errors; asymptomatic and hospital-admission assessments are limited because most users test only when symptomatic and severe hospitalised cases may not self-report, and mortality could not be assessed.
  • The paper states that reinfection was inferred from test timing rather than sequencing, prolonged PCR positivity cannot be ruled out, and seasonal effects may not have been fully accounted for despite adjustment for temperature and humidity.

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

Integrity signals

Registry

Crossref · 10.1016/s2468-2667(21)00055-4

Cites

24 of 25 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 18 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Possible reinfections were identified in 249 (0.7% [95% CI 0.6-0.8]) of 36,509 app users who reported a positive swab test before Oct 1, 2020.

    “For the same period, possible reinfections were identified in 249 (0·7% [95% CI 0·6–0·8]) of 36 509 app users who reported a positive swab test before Oct 1, 2020”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The COVID Symptom Study app users are representative of the UK population for assessing symptoms and reinfection rates.
    • Rests on an assumption: Self-reported positive tests and symptom logs in the app are accurate enough to measure infection and symptoms.
  • Findingown data

    The effective reproduction number Rt of the B.1.1.7 variant showed a multiplicative increase by a factor of 1.35 (95% CI 1.02-1.69) relative to pre-existing variants.

    “We found a multiplicative increase in the Rt of B.1.1.7 by a factor of 1·35 (95% CI 1·02–1·69) relative to pre-existing variants.”
    • Also stated in: § Introduction · plain
      “We found a multiplicative increase in the effective reproduction number, Rt, of the B.1.1.7 variant by a factor of 1·35 (95% CI 1·02–1·69) compared with pre-existing variants.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The COG-UK sequencing sample is representative of all SARS-CoV-2 cases in the regions.
  • Findingown data

    Rt fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant.

    “However, Rt fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant.”
    • Also stated in: § Introduction · plain
      “However, we found that Rt fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The COG-UK sequencing sample is representative of all SARS-CoV-2 cases in the regions.
  • Findingown data

    From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36,920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up.

    “From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36 920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up.”
    • Also stated in: § Results · plain
      “we investigated the symptom reports of the 36 920 of those with a positive test whose region was known and who reported as healthy on app sign-up.”
    Quote in the paperSubstantial claim
  • Findingown data

    There was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants.

    “but there was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The COVID Symptom Study app users are representative of the UK population for assessing symptoms and reinfection rates.
    • Rests on an assumption: The regional proportion of B.1.1.7 infections is a valid proxy for the variant infecting individual app users in that region.
    • Rests on an assumption: Self-reported positive tests and symptom logs in the app are accurate enough to measure infection and symptoms.
  • May combine two claims. 12
  • Classified as probably not a substantial claim. 15

  • May combine two claims.

    Findingown data

    Considering the mean of the rolling average across December, 2020, the three regions with the largest proportion of infections with the B.1.1.7 variant were the South East, London, and East of England, and the three regions with the lowest proportion were Wales, the North East and Yorkshire, and the North West.

    “Considering the mean of the rolling average across December, 2020, the three regions with the largest proportion of infections with the B.1.1.7 variant were the South East, London, and East of England. The three regions with the lowest proportion were Wales, the North East and Yorkshire, and the North West.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The COG-UK sequencing sample is representative of all SARS-CoV-2 cases in the regions.

  • May combine two claims.

    Findingcitation

    Between Sept 27 and Dec 31, 2020, 98,170 sequences were made available by COG-UK, corresponding to 4.4% of the 2,207,476 cases recorded during this period, and 16,224 (16.5%) sequences were of variant B.1.1.7.

    “Between Sept 27 and Dec 31, 2020, 98 170 sequences were made available by COG-UK, corresponding to 4·4% of the 2 207 476 cases recorded during this period.12 16 224 (16·5%) sequences were of variant B.1.1.7.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] Public Health England UK COVID-19 dashboard https://coronavirus.data.gov.uk/

      Not checked in the free run.

    • Rests on an assumption: The COG-UK sequencing sample is representative of all SARS-CoV-2 cases in the regions.

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

    Findingreasoning

    In January 2021, the proportion of infections with the B.1.1.7 variant in London, the South East, and the East of England was at least 80%, assuming the proportion had not decreased from the end of December.

    “In January, the proportion of infections with the B.1.1.7 variant in London, the South East, and the East of England (these three regions had the largest proportion of infections with the B.1.1.7 variant in England) was at least 80%, assuming the proportion had not decreased from the end of December.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The proportion of infections with the B.1.1.7 variant in London, the South East, and the East of England had not decreased from the end of December 2020 to January 2021.

  • May combine two claims.

    Premisecitation

    The B.1.1.7 variant increases the risk of admission to hospital and death.

    “Evidence suggests that the B.1.1.7 variant increases the risk of admission to hospital and death.6”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) on SARS-CoV-2 variant B.1.1.7. NERVTAG: update note on B.1.1.7 severity https://www.gov.uk/government/publications/nervtag-update-note-on-b117-severity-11-february-2021 Feb 12, 2021

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    In the period Sept 28 to Dec 27, 2020, 497,989 users reported a swab test, of whom 55,192 reported a positive test, and 36,920 of those with a positive test whose region was known and who reported as healthy on app sign-up were investigated for symptom reports.

    “In the same period, 497 989 users reported a swab test, of whom 55 192 reported a positive test, and we investigated the symptom reports of the 36 920 of those with a positive test whose region was known and who reported as healthy on app sign-up.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductnone given

    The drop in reporting of fever in early November was caused by a change in the wording of the question, and the wording was subsequently reverted a week later.

    “The drop in reporting of fever in early November was caused by a change in the wording of the question; this wording was subsequently reverted a week later.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data

    The analyses adjusted for age and sex of users, and for regional temperature and humidity.

    “We adjusted for the age and sex of users, as well as for two seasonal environmental confounders: regional temperature and humidity.”
    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 conductnone given

    Respondents signing up to a participatory platform such as the COVID Symptom Study app are likely to be more interested in health and COVID-19 than the wider population, and might exhibit different behaviours.

    “For example, respondents signing up to a participatory platform such as the COVID Symptom Study app are likely to be more interested in health and COVID-19 than the wider population, and might exhibit different behaviours.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The B.1.1.7 variant has been spreading rapidly, with cases increasing in frequency.

    “Genomic surveillance revealed that this new variant, termed B.1.1.7, has several mutations of immunological significance and has been spreading rapidly, with cases increasing in frequency.2”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Public Health England Investigation of novel SARS-COV-2 variant: variant of concern 202012/01. Technical briefing 2 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/959361/Technical_Briefing_VOC202012-2_Briefing_2.pdf Dec 28, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Repeated positive testing has been reported shortly after hospital discharge, with PCR positivity detected up to 28 days after symptom resolution.

    “Repeated positive testing has been reported shortly after hospital discharge,27 with PCR positivity detected up to 28 days after symptom resolution.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [27] Zheng J Zhou R Chen F Incidence, clinical course and risk factor for recurrent PCR positivity in discharged COVID-19 patients in Guangzhou, China: a prospective cohort study PLoS Negl Trop Dis 14 2020 e0008648 PMC7505432 32866168

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Our data provide a complementary measure to existing measurements of increased transmissibility of the B.1.1.7 variant by using real-time, representative incidence estimates to measure Rt, whereas other studies have relied on lagged deaths and admissions or community case numbers that do not reflect true infection numbers.

    “Our data also offer the ability to provide a valuable complementary measure to existing measurements of the increased transmissibility of the B.1.1.7 variant: we were able to use real-time, representative incidence estimates to measure Rt, whereas other studies have relied on deaths and admissions to hospital, which are lagged, or community case numbers, which do not reflect true infection numbers”
    Quote in the paperSubstantial claim

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

    Study design and conductreasoning

    Although we were able to correct for some demographic factors such as age and sex, others are more difficult to characterise and correct for.

    “Although we were able to correct for some of these factors, such as age and sex, in our analysis, others are more difficult to characterise and correct for.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Previous publications from our group have found that population-level estimates of disease prevalence from our app triangulate well with those obtained from studies designed to be representative of the population.

    “Previous publications from our group have found that population-level estimates of disease prevalence from our app triangulate well with those obtained from studies designed to be representative of the population.11”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [11] Varsavsky T Graham MS Canas LS Detecting COVID-19 infection hotspots in England using large-scale self-reported data from a mobile application: a prospective, observational study Lancet Public Health 6 2021 e21 e29 33278917 PMC7785969

      Not checked in the free run.

  • May combine two claims.

    Study design and conductreasoning

    The chosen cutoff of 90 days between two positive tests is unlikely to be due to prolonged PCR positivity, but this cannot be ruled out and would probably only affect a small number of cases.

    “Although the chosen cutoff of 90 days between two positive tests is unlikely to be due to prolonged PCR positivity, this cannot be ruled out; however, this would probably only affect a small number of cases.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Davies and colleagues found the B.1.1.7 variant to be 43-90% (95% CI 38-130) more transmissible than pre-existing variants.

    “Davies and colleagues4 found the B.1.1.7 variant to be 43–90% (95% CI 38–130) more transmissible than pre-existing variants”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [4] Davies NG Abbott S Barnard RC Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England Science 2021 published online March 3. 10.1126/science.abg3055 PMC8128288 33658326 source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductown data

    The large, longitudinal nature of the COVID Symptom Study data, with good coverage of the UK population, provides a unique opportunity to study potential changes in symptomatology and disease duration.

    “The large, longitudinal nature of the COVID Symptom Study data, with good coverage of the UK population, provides a unique opportunity to study potential changes in symptomatology and disease duration.”
    Quote in the paperSubstantial claim

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

    Study design and conductreasoning

    After exclusions, 1,767,914 users remained in the study.

    “We excluded users living in Northern Ireland because of the low number of users who signed up (38 976 users), as well as 383 352 users without information on sex, and 2 175 979 who had not logged responses in the app between Sept 28 and Dec 27, 2020, leaving a total of 1 767 914 users.”
    Quote in the paperNot a substantial claim

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

    Study design and conductnone given

    The analyses controlled for the false discovery rate to account for multiple comparisons.

    “We controlled for the false discovery rate to account for multiple comparisons.”
    Quote in the paperNot a substantial claim

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

    Interpretationreasoning

    The discrepancy between our results and those of the COVID-19 Infection Survey might be explained by sampling at different points in the disease course.

    “The discrepancy between our results and those of the COVID-19 Infection Survey might be explained by sampling at different points in the disease course.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Spike-gene target failure (SGTF) is a marker that is sensitive, but not necessarily specific, to the B.1.1.7 variant, as other circulating variants also contain the mutation leading to an SGTF.

    “This failure results in a marker that is sensitive, but not necessarily specific, to the B.1.1.7 variant, as other circulating variants also contain the mutation leading to an SGTF.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Public Health England Investigation of novel SARS-COV-2 variant: variant of concern 202012/01. Technical briefing 1 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/959438/Technical_Briefing_VOC_SH_NJL2_SH2.pdf Dec 21, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation

    Preliminary evidence from epidemiological studies suggests that the B.1.1.7 variant is more transmissible than pre-existing variants.

    “Preliminary evidence from epidemiological studies suggests that the B.1.1.7 variant is more transmissible than pre-existing variants.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [4] Davies NG Abbott S Barnard RC Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England Science 2021 published online March 3. 10.1126/science.abg3055 PMC8128288 33658326 source

      Not checked in the free run.

    • cites [5] Volz E Mishra S Chand M Assessing transmissibility of SARS-CoV-2 lineage B.1.1.7 in England Nature 2021 published online March 25. 10.1038/s41586-021-03470-x 33767447 source

      Not checked in the free run.

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

    Premisecitation

    Data obtained from participatory digital platforms have well-documented biases in demographics.

    “Second, data obtained from participatory digital platforms have well documented25 biases in demographics.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [25] Baltrusaitis K Santillana M Crawley AW Chunara R Smolinski M Brownstein JS Determinants of participants' follow-up and characterization of representativeness in flu near you, a participatory disease surveillance system JMIR Public Health Surveill 3 2017 e18 28389417 PMC5400887

      Not checked in the free run.

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

    Study design and conductreasoning

    The design of the app seeks to minimise data input errors by showing users their full test history and allowing them to amend incorrect entries.

    “Self-report also carries the risk of data input errors, although the design of the app seeks to minimise this; for example, each time a user submits a log in the app, they are shown the full history of their test results and are given the option to amend incorrect entries.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Participatory studies might suffer from ascertainment or collider bias.

    “Participatory studies might also suffer from ascertainment or collider bias.26”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [26] Griffith GJ Morris TT Tudball MJ Collider bias undermines our understanding of COVID-19 disease risk and severity Nat Commun 11 2020 5749 PMC7665028 33184277

      Not checked in the free run.

24 of 24

  • The paper relies on this without support.

    The COVID Symptom Study app users are representative of the UK population for assessing symptoms and reinfection rates.

    “We used data from the COVID Symptom Study,7 a longitudinal dataset providing symptom reports and test results from a population of more than 4 million adults living in the UK”
    “We included users living in the UK who had logged responses through the app at least once in the period between Sept 28 and Dec 27, 2020.”

  • The paper relies on this without support.

    The regional proportion of B.1.1.7 infections is a valid proxy for the variant infecting individual app users in that region.

    “We did ecological studies to assess the symptoms, disease course, rates of reinfection, and transmissibility associated with increasing proportions of infections with the B.1.1.7 variant in the UK population.”

  • The paper relies on this without support.

    Vaccine-induced immunity and immunity from natural infection are similar enough that lack of increased reinfection implies vaccines remain effective against B.1.1.7.

    “given that there was no apparent increase in the reinfection rate, vaccines are likely to remain effective against the B.1.1.7 variant.”

  • The paper relies on this without support.

    Self-reported positive tests and symptom logs in the app are accurate enough to measure infection and symptoms.

    “Users are asked to record each day whether they feel physically normal and, if not, to log any symptoms. After a user reports any symptoms, they are asked “Where are you right now?”, with the options “At home”, “At hospital with suspected COVID-19 symptoms”, or “Back from hospital”. Users are also asked to maintain a record of any COVID-19 tests and their date, type, and result in the app.”

  • The paper relies on this without support.

    The COG-UK sequencing sample is representative of all SARS-CoV-2 cases in the regions.

    “These data were produced by sequencing a sample of PCR tests done in the community.”

  • The authors state this as an assumption.

    The proportion of infections with the B.1.1.7 variant in London, the South East, and the East of England had not decreased from the end of December 2020 to January 2021.

    “assuming the proportion had not decreased from the end of December.”

  • The authors state this as an assumption.

    All non-B.1.1.7 variants in circulation at the time of study give rise to the same range of symptoms and immune response, and have the same transmissibility.

    “Our work assumes that all non-B.1.1.7 variants in circulation at the time of study give rise to the same range of symptoms and immune response, and have the same transmissibility.”

  • The authors state this as an assumption.

    Testing positive for SARS-CoV-2 infection after an interval of 90 days with at least a 7-day period with an absence of symptoms is consistent with reinfection.

    “Another limitation was that we assumed that testing positive for SARS-CoV-2 infection after an interval of 90 days with at least a 7-day period with an absence of symptoms is consistent with reinfection.”
8 of 8

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?

  • The Alpha variant is rarely associated with reduced susceptibility to convalescent plasma, consistent with it not being associated with an increased risk of reinfection.

    “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 .”

    From The biological and clinical significance of emerging SARS-CoV-2 variants (2021) · cites this paper as [207]

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.

  • Long symptom duration has conflicting 28-day thresholds

    Minor

    The methods define long symptom duration as lasting at least 28 days, but the discussion defines it as lasting more than 28 days. These definitions disagree for a duration of exactly 28 days.

  • Reinfection results use different minimum intervals from the definition

    Minor

    The definition requires tests separated by more than 90 days and more than 7 symptom-free days, whereas the results describe including intervals of at least 90 and at least 7 days. Cases exactly at either threshold would be treated differently.

2 of 2

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Graham, M. S., Sudre, C. H., May, A., Antonelli, M., Murray, B., Varsavsky, T., Kläser, K., Canas, L. S., Molteni, E., Modat, M., Drew, D. A., Nguyen, L. H., Polidori, L., Selvachandran, S., Hu, C., Capdevila, J., Koshy, C., Ash, A., Wise, E., Moore, N., Mori, M., Cortes, N., Lynch, J., Kidd, S., Fairley, D. J., Curran, T., McKenna, J. P., Adams, H., Fraser, C., Golubchik, T., Bonsall, D., Hassan-Ibrahim, M. O., Malone, C. S., Cogger, B. J., Wantoch, M., Reynolds, N., Warne, B., Maksimovic, J., Spellman, K., McCluggage, K., John, M., Beer, R., Afifi, S., Morgan, S., Marchbank, A., Price, A., Kitchen, C., Gulliver, H., Merrick, I., Southgate, J., Guest, M., Munn, R., Workman, T., Connor, T. R., Fuller, W., Bresner, C., Snell, L. B., Patel, A., Charalampous, T., Nebbia, G., Batra, R., Edgeworth, J., Robson, S. C., Beckett, A. H., Aanensen, D. M., Underwood, A. P., Yeats, C. A., Abudahab, K., Taylor, B. E., Menegazzo, M., Clark, G., Smith, W., Khakh, M., Fleming, V. M., Lister, M. M., Howson-Wells, H. C., Berry, L., Boswell, T., Joseph, A., Willingham, I., Jones, C., Holmes, C., Bird, P., Helmer, T., Fallon, K., Tang, J., Raviprakash, V., Campbell, S., Sheriff, N., Blakey, V., Williams, L.-A., Loose, M. W., Holmes, N., Moore, C., Carlile, M., Wright, V., Sang, F., Debebe, J., Coll, F., Signell, A. W., Betancor, G., Wilson, H. D., Eldirdiri, S., Kenyon, A., Davis, T., Pybus, O. G., du Plessis, L., Zarebski, A. E., Raghwani, J., Kraemer, M. U., Francois, S., Attwood, S. W., Vasylyeva, T. I., Escalera Zamudio, M., Gutierrez, B., Torok, M. E., Hamilton, W. L., Goodfellow, I. G., Hall, G., Jahun, A. S., Chaudhry, Y., Hosmillo, M., Pinckert, M. L., Georgana, I., Moses, S., Lowe, H., Bedford, L., Moore, J., Stonehouse, S., Fisher, C. L., Awan, A. R., BoYes, J., Breuer, J., Harris, K. A., Brown, J. R., Shah, D., Atkinson, L., Lee, J. C., Storey, N., Flaviani, F., Alcolea-Medina, A., Williams, R., Vernet, G., Chapman, M. R., Levett, L. J., Heaney, J., Chatterton, W., Pusok, M., Xu-McCrae, L., Smith, D. L., Bashton, M., Young, G. R., Holmes, A., Randell, P. A., Cox, A., Madona, P., Bolt, F., Price, J., Mookerjee, S., Ragonnet-Cronin, M., Nascimento, F. F., Jorgensen, D., Siveroni, I., Johnson, R., Boyd, O., Geidelberg, L., Volz, E. M., Rowan, A., Taylor, G. P., Smollett, K. L., Loman, N. J., Quick, J., McMurray, C., Stockton, J., Nicholls, S., Rowe, W., Poplawski, R., McNally, A., Martinez Nunez, R. T., Mason, J., Robinson, T. I., O'Toole, E., Watts, J., Breen, C., Cowell, A., Sluga, G., Machin, N. W., Ahmad, S. S. Y., George, R. P., Halstead, F., Sivaprakasam, V., Hogsden, W., Illingworth, C. J., Jackson, C., Thomson, E. C., Shepherd, J. G., Asamaphan, P., Niebel, M. O., Li, K. K., Shah, R. N., Jesudason, N. G., Tong, L., Broos, A., Mair, D., Nichols, J., Carmichael, S. N., Nomikou, K., Aranday-Cortes, E., Johnson, N., Starinskij, I., da Silva Filipe, A., Robertson, D. L., Orton, R. J., Hughes, J., Vattipally, S., Singer, J. B., Nickbakhsh, S., Hale, A. D., Macfarlane-Smith, L. R., Harper, K. L., Carden, H., Taha, Y., Payne, B. A., Burton-Fanning, S., Waugh, S., Collins, J., Eltringham, G., Rushton, S., O'Brien, S., Bradley, A., Maclean, A., Mollett, G., Blacow, R., Templeton, K. E., McHugh, M. P., Dewar, R., Wastenge, E., Dervisevic, S., Stanley, R., Meader, E. J., Coupland, L., Smith, L., Graham, C., Barton, E., Padgett, D., Scott, G., Swindells, E., Greenaway, J., Nelson, A., McCann, C. M., Yew, W. C., Andersson, M., Peto, T., Justice, A., Eyre, D., Crook, D., Sloan, T. J., Duckworth, N., Walsh, S., Chauhan, A. J., Glaysher, S., Bicknell, K., Wyllie, S., Elliott, S., Lloyd, A., Impey, R., Levene, N., Monaghan, L., Bradley, D. T., Wyatt, T., Allara, E., Pearson, C., Osman, H., Bosworth, A., Robinson, E., Muir, P., Vipond, I. B., Hopes, R., Pymont, H. M., Hutchings, S., Curran, M. D., Parmar, S., Lackenby, A., Mbisa, T., Platt, S., Miah, S., Bibby, D., Manso, C., Hubb, J., Chand, M., Dabrera, G., Ramsay, M., Bradshaw, D., Thornton, A., Myers, R., Schaefer, U., Groves, N., Gallagher, E., Lee, D., Williams, D., Ellaby, N., Harrison, I., Hartman, H., Manesis, N., Patel, V., Bishop, C., Chalker, V., Ledesma, J., Twohig, K. A., Holden, M. T. G., Shaaban, S., Birchley, A., Adams, A., Davies, A., Gaskin, A., Plimmer, A., Gatica-Wilcox, B., McKerr, C., Moore, C., Williams, C., Heyburn, D., De Lacy, E., Hilvers, E., Downing, F., Shankar, G., Jones, H., Asad, H., Coombes, J., Watkins, J., Evans, J. M., Fina, L., Gifford, L., Gilbert, L., Graham, L., Perry, M., Morgan, M., Bull, M., Cronin, M., Pacchiarini, N., Craine, N., Jones, R., Howe, R., Corden, S., Rey, S., Kumziene-SummerhaYes, S., Taylor, S., Cottrell, S., Jones, S., Edwards, S., O'Grady, J., Page, A. J., Mather, A. E., Baker, D. J., Rudder, S., Aydin, A., Kay, G. L., Trotter, A. J., Alikhan, N.-F., de Oliveira Martins, L., Le-Viet, T., Meadows, L., Casey, A., Ratcliffe, L., Simpson, D. A., Molnar, Z., Thompson, T., Acheson, E., Masoli, J. A., Knight, B. A., Ellard, S., Auckland, C., Jones, C. R., Mahungu, T. W., Irish-Tavares, D., Haque, T., Hart, J., Witele, E., Fenton, M. L., Dadrah, A., Symmonds, A., Saluja, T., Bourgeois, Y., Scarlett, G. P., Loveson, K. F., Goudarzi, S., Fearn, C., Cook, K., Dent, H., Paul, H., Partridge, D. G., Raza, M., Evans, C., Johnson, K., Liggett, S., Baker, P., Bonner, S., Essex, S., Lyons, R. A., Saeed, K., Mahanama, A. I. K., Samaraweera, B., Silveira, S., Pelosi, E., Wilson-Davies, E., Williams, R. J., Kristiansen, M., Roy, S., Williams, C. A., Cotic, M., Bayzid, N., Westhorpe, A. P., Hartley, J. A., Jannoo, R., Lowe, H. L., Karamani, A., Ensell, L., Prieto, J. A., Jeremiah, S., Grammatopoulos, D., Pandey, S., Berry, L., Jones, K., Richter, A., Beggs, A., Best, A., Percival, B., Mirza, J., Megram, O., Mayhew, M., Crawford, L., Ashcroft, F., Moles-Garcia, E., Cumley, N., Smith, C. P., Bucca, G., Hesketh, A. R., Blane, B., Girgis, S. T., Leek, D., Sridhar, S., Forrest, S., Cormie, C., Gill, H. K., Dias, J., Higginson, E. E., Maes, M., Young, J., Kermack, L. M., Gupta, R. K., Ludden, C., Peacock, S. J., Palmer, S., Churcher, C. M., Hadjirin, N. F., Carabelli, A. M., Brooks, E., Smith, K. S., Galai, K., McManus, G. M., Ruis, C., Davidson, R. K., Rambaut, A., Williams, T., Balcazar, C. E., Gallagher, M. D., O'Toole, Á., Rooke, S., Hill, V., Williamson, K. A., Stanton, T. D., Michell, S. L., Bewshea, C. M., Temperton, B., Michelsen, M. L., Warwick-Dugdale, J., Manley, R., Farbos, A., Harrison, J. W., Sambles, C. M., Studholme, D. J., Jeffries, A. R., Darby, A. C., Hiscox, J. A., Paterson, S., Iturriza-Gomara, M., Jackson, K. A., Lucaci, A. O., Vamos, E. E., Hughes, M., Rainbow, L., Eccles, R., Nelson, C., Whitehead, M., Turtle, L., Haldenby, S. T., Gregory, R., Gemmell, M., Wierzbicki, C., Webster, H. J., de Silva, T. I., Smith, N., Angyal, A., Lindsey, B. B., Groves, D. C., Green, L. R., Wang, D., Freeman, T. M., Parker, M. D., Keeley, A. J., Parsons, P. J., Tucker, R. M., Brown, R., Wyles, M., Whiteley, M., Zhang, P., Gallis, M., Louka, S. F., Constantinidou, C., Unnikrishnan, M., Ott, S., Cheng, J. K. J., Bridgewater, H. E., Frost, L. R., Taylor-Joyce, G., Stark, R., Baxter, L., Alam, M. T., Brown, P. E., Aggarwal, D., Cerda, A. C., Merrill, T. V., Wilson, R. E., McClure, P. C., Chappell, J. G., Tsoleridis, T., Ball, J., Buck, D., Todd, J. A., Green, A., Trebes, A., MacIntyre-Cockett, G., de Cesare, M., Alderton, A., Amato, R., Ariani, C. V., Beale, M. A., Beaver, C., Bellis, K. L., Betteridge, E., Bonfield, J., Danesh, J., Dorman, M. J., Drury, E., Farr, B. W., Foulser, L., Goncalves, S., Goodwin, S., Gourtovaia, M., Harrison, E. M., Jackson, D. K., Jamrozy, D., Johnston, I., Kane, L., Kay, S., Keatley, J.-P., Kwiatkowski, D., Langford, C. F., Lawniczak, M., Letchford, L., Livett, R., Lo, S., Martincorena, I., McGuigan, S., Nelson, R., Palmer, S., Park, N. R., Patel, M., Prestwood, L., Puethe, C., Quail, M. A., Rajatileka, S., Scott, C., Shirley, L., Sillitoe, J., Spencer Chapman, M. H., Thurston, S. A., Tonkin-Hill, G., Weldon, D., Rajan, D., Bronner, I. F., Aigrain, L., Redshaw, N. M., Lensing, S. V., Davies, R., Whitwham, A., Liddle, J., Lewis, K., Tovar-Corona, J. M., Leonard, S., Durham, J., Bassett, A. R., McCarthy, S., Moll, R. J., James, K., Oliver, K., Makunin, A., Barrett, J., Gunson, R. N., Hammers, A., Chan, A. T., Wolf, J., Spector, T. D., Steves, C. J., & Ourselin, S.
Affiliations
  • King's College London (GB)
  • ZOE (United Kingdom) (GB)
  • Harvard University (US)
Corresponding author
Graham, Mark S
ORCID
Venue
The Lancet Public Health
Publisher
Elsevier BV
Published
2021-05
Volume
6
Issue
5
Pages
e335-e345
ISSN
2468-2667 (ISSN-L)
DOI
10.1016/s2468-2667(21)00055-4
PMC
PMC8041365
OpenAlex
W3155952134
Semantic Scholar
15e9050536b354de7a7b4118467db8026e190ed4
Cited by
304
References
25
Citations by year
2026: 7 · 2025: 11 · 2024: 28 · 2023: 37 · 2022: 115 · 2021: 106
FWCI
22.65
Type
journal article
Language
en
Open access
Licence
Locations
  • The Lancet Public Health (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • ePrints Soton (University of Southampton) (acceptedVersion)
  • UEA Digital Repository (University of East Anglia) (acceptedVersion)
  • Cronfa (Swansea University) (acceptedVersion)
  • ENLIGHTEN (Jurnal Bimbingan dan Konseling Islam) (acceptedVersion, cc-by-sa)
  • LSHTM Research Online (London School of Hygiene and Tropical Medicine) (acceptedVersion)
  • Acceda (Universidad de Las Palmas de Gran Canaria) (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • IRIS eCampus Telematic University (Università degli Studi eCampus) (submittedVersion)
  • Research Portal (King's College London) (submittedVersion, cc-by)
  • University of Birmingham Research Portal (University of Birmingham) (submittedVersion, cc-by)
  • Spiral (Imperial College London) (submittedVersion, other-oa)
Funders
  • MRC
  • Wellcome Trust
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
COVID-19 pandemic, symptomatology, reinfection, transmissibility, effective reproduction number, clinical course, COVID-19 incidence, United Kingdom
MeSH terms
Reinfection, COVID-19, SARS-CoV-2, Adolescent, Adult, Aged, Female, United Kingdom, Humans, Male, Middle Aged, Young Adult

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