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Cited by 1,389SARS-CoV-2 and COVID-19 ResearchVaccine Coverage and HesitancyCOVID-19 Clinical Research Studies

Effectiveness of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines on covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study

Open access
Lopez Bernal, Jamie, Andrews, Nick, Gower, Charlotte, Robertson, Chris, Stowe, Julia, Tessier, Elise, Simmons, Ruth, Cottrell, Simon +7 more·2021·BMJ
DOI 10.1136/bmj.n1088PMC PMC8116636

Published version of a preprint

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Abstract

Objective: To estimate the real world effectiveness of the Pfizer-BioNTech BNT162b2 and Oxford-AstraZeneca ChAdOx1-S vaccines against confirmed covid-19 symptoms (including the UK variant of concern B.1.1.7), admissions to hospital, and deaths. Design: Test negative case-control study. Setting: Community testing for covid-19 in England. Participants: 156 930 adults aged 70 years and older who reported symptoms of covid-19 between 8 December 2020 and 19 February 2021 and were successfully linked to vaccination data in the National Immunisation Management System. Interventions: Vaccination with BNT162b2 or ChAdOx1-S. Main outcome measures: Primary outcomes were polymerase chain reaction confirmed symptomatic SARS-CoV-2 infections, admissions to hospital for covid-19, and deaths with covid-19. Results: Participants aged 80 years and older vaccinated with BNT162b2 before 4 January 2021 had a higher odds of testing positive for covid-19 in the first nine days after vaccination (odds ratio up to 1.48, 95% confidence interval 1.23 to 1.77), indicating that those initially targeted had a higher underlying risk of infection. Vaccine effectiveness was therefore compared with the baseline post-vaccination period. Vaccine effects were noted 10 to 13 days after vaccination, reaching a vaccine effectiveness of 70% (95% confidence interval 59% to 78%), then plateauing. From 14 days after the second dose a vaccination effectiveness of 89% (85% to 93%) was found compared with the increased baseline risk. Participants aged 70 years and older vaccinated from 4 January (when ChAdOx1-S delivery commenced) had a similar underlying risk of covid-19 to unvaccinated individuals. With BNT162b2, vaccine effectiveness reached 61% (51% to 69%) from 28 to 34 days after vaccination, then plateaued. With ChAdOx1-S, effects were seen from 14 to 20 days after vaccination, reaching an effectiveness of 60% (41% to 73%) from 28 to 34 days, increasing to 73% (27% to 90%) from day 35 onwards. On top of the protection against symptomatic disease, a further 43% (33% to 52%) reduced risk of emergency hospital admission and 51% (37% to 62%) reduced risk of death was observed in those who had received one dose of BNT162b2. Participants who had received one dose of ChAdOx1-S had a further 37% (3% to 59%) reduced risk of emergency hospital admission. Follow-up was insufficient to assess the effect of ChAdOx1-S on mortality. Combined with the effect against symptomatic disease, a single dose of either vaccine was about 80% effective at preventing admission to hospital with covid-19 and a single dose of BNT162b2 was 85% effective at preventing death with covid-19. Conclusion: Vaccination with either one dose of BNT162b2 or ChAdOx1-S was associated with a significant reduction in symptomatic covid-19 in older adults, and with further protection against severe disease. Both vaccines showed similar effects. Protection was maintained for the duration of follow-up (>6 weeks). A second dose of BNT162b2 was associated with further protection against symptomatic disease. A clear effect of the vaccines against the B.1.1.7 variant was found.

AI snapshot

Written from the paper’s full text.

TL;DR

In a test negative case-control study of 156,930 adults aged ≥70 in England, one dose of BNT162b2 or ChAdOx1-S reduced symptomatic covid-19, with additional protection against hospital admission and death. Both vaccines showed similar early effectiveness, including against the B.1.1.7 variant, though follow-up was limited.

Key findings

  • Among 156,930 linked participants, 44,590 (28.4%) tested positive and 112,340 (71.6%) tested negative; BNT162b2 given before 4 January in adults ≥80 showed higher early odds of testing positive (OR up to 1.48, 95% CI 1.23 to 1.77 at days 7-9), then vaccine effectiveness reached 70% (59% to 78%) at 10-13 days and 89% (85% to 93%) from 14 days after the second dose compared with the increased baseline risk.
  • From 4 January in adults ≥70, BNT162b2 effectiveness reached 61% (51% to 69%) at 28-34 days after one dose; ChAdOx1-S effectiveness reached 60% (41% to 73%) at 28-34 days and 73% (27% to 90%) from day 35 onwards.
  • Among those who had received one dose of BNT162b2, there was a further 43% (33% to 52%) reduced risk of emergency hospital admission and 51% (37% to 62%) reduced risk of death; one dose of ChAdOx1-S had a further 37% (3% to 59%) reduced risk of emergency hospital admission.
  • Combined with protection against symptomatic disease, a single dose of either vaccine was about 80% effective at preventing hospital admission, and a single dose of BNT162b2 was 85% effective at preventing death; a clear effect against the B.1.1.7 variant was found.

Methods

  • Test negative case-control study using community PCR testing in England, linked to vaccination histories in the National Immunisation Management System and to hospital admission and mortality data.
  • Included 156,930 adults aged ≥70 who reported covid-19 symptoms between 8 December 2020 and 19 February 2021 and were successfully linked to vaccination data; analyses used narrow post-vaccination intervals.
  • Logistic regression estimated odds of vaccination in PCR-confirmed cases versus test-negative controls, adjusted for age, sex, ethnicity, NHS region, index of multiple deprivation, care home residence, and week of symptom onset; proportional hazards survival analyses assessed hospital admission and death.

Limitations

  • The paper states that the observational design leaves confounding possible, including higher underlying risk among early vaccinees, healthy vaccinee effects, deferral of vaccination in unwell or exposed people, and misclassification from self-reported symptoms, PCR test performance, and vaccination data lags; it also notes limited follow-up, lower linkage for non-white and ≥85 groups, and restriction to symptomatic disease.
  • The paper states that follow-up was insufficient to assess ChAdOx1-S effect on mortality, and that ChAdOx1-S estimates had wide confidence intervals and had not clearly plateaued.
  • Evident from the text: B.1.1.7 identification relied on spike gene target failure as a proxy rather than sequencing, and the study could not assess asymptomatic infection or transmission.

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

Integrity signals

Registry

Crossref · 10.1136/bmj.n1088

Cites

Statistics

Nothing to recompute.

Claims the paper makes

0 of 15 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Participants aged 70 years and older vaccinated from 4 January had a similar underlying risk of covid-19 to unvaccinated individuals.

    “Participants aged 70 years and older vaccinated from 4 January (when ChAdOx1-S delivery commenced) had a similar underlying risk of covid-19 to unvaccinated individuals.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.
  • Findingown data

    From 14 days after the second dose, vaccine effectiveness was 89% (85% to 93%) compared with the increased baseline risk.

    “From 14 days after the second dose a vaccination effectiveness of 89% (85% to 93%) was found compared with the increased baseline risk.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.
  • Findingown data

    Vaccination with either one dose of BNT162b2 or ChAdOx1-S was associated with further protection against severe disease.

    “Vaccination with either one dose of BNT162b2 or ChAdOx1-S was associated with a significant reduction in symptomatic covid-19 in older adults, and with further protection against severe disease.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.
  • Findingown data

    In the analysis of vaccinations from 4 January, no significantly increased risk was observed during the early post-vaccination period for either vaccine.

    “In this analysis, no significantly increased risk was observed during the early post-vaccination period for either vaccine.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.
  • Findingown data

    A second dose of BNT162b2 was associated with further protection against symptomatic disease.

    “A second dose of BNT162b2 was associated with further protection against symptomatic disease.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.
  • May combine two claims. 26
  • Classified as probably not a substantial claim. 14

  • May combine two claims.

    Findingown data

    Overall, 174 731 pillar 2 PCR tested samples were available for people who reported symptoms within 10 days of the sample date; 156 930 of these (89.8%) were successfully linked to vaccination data in NIMS-44 590 (28.4%) tested positive for covid-19 and 112 340 (71.6%) tested negative.

    “Overall, 174 731 pillar 2 PCR tested samples were available for people who reported symptoms within 10 days of the sample date; 156 930 of these (89.8%) were successfully linked to vaccination data in NIMS—44 590 (28.4%) tested positive for covid-19 and 112 340 (71.6%) tested negative.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    With ChAdOx1-S, effects were seen from 14 to 20 days after vaccination, reaching an effectiveness of 60% (41% to 73%) from 28 to 34 days, increasing to 73% (27% to 90%) from day 35 onwards.

    “With ChAdOx1-S, effects were seen from 14 to 20 days after vaccination, reaching an effectiveness of 60% (41% to 73%) from 28 to 34 days, increasing to 73% (27% to 90%) from day 35 onwards.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    The odds ratios began to decrease from 10 to 13 days after vaccination, reaching 0.41 (0.32 to 0.54) on days 28 to 34, and remained at a similar level from 35 days onwards.

    “The odds ratios then began to decrease from 10 to 13 days after vaccination, reaching 0.41 (0.32 to 0.54) on days 28 to 34, and remained at a similar level from 35 days onwards.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    The odds ratios began to decrease from 14 days after vaccination, reaching 0.50 (95% CI 0.42 to 0.59) during days 28 to 34, and remained stable thereafter.

    “The odds ratios then began to decrease from 14 days after vaccination, reaching 0.50 (95% confidence interval 0.42 to 0.59) during days 28 to 34, and remained stable thereafter.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

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

    Findingown data

    Characteristics of participants with linked and unlinked test data were generally similar, although a higher proportion of people of non-white ethnicity and aged 85 years and older were among those with no linked test data.

    “Characteristics were generally similar, although a higher proportion of people of non-white ethnicity and aged 85 years and older were among those with no linked test data.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    From seven days after a second dose of BNT162b2, the odds ratio was 0.21 (0.14 to 0.32) and then 0.15 (0.11 to 0.21) from 14 days after the second dose, indicating a vaccine effectiveness of 85%.

    “From seven days after a second dose of BNT162b2, the odds ratio was 0.21 (0.14 to 0.32) and then 0.15 (0.11 to 0.21) from 14 days after the second dose, indicating a vaccine effectiveness of 85%.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    With BNT162b2, vaccine effectiveness reached 61% (51% to 69%) from 28 to 34 days after vaccination, then plateaued.

    “With BNT162b2, vaccine effectiveness reached 61% (51% to 69%) from 28 to 34 days after vaccination, then plateaued.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    Vaccine effects were noted 10 to 13 days after vaccination, reaching a vaccine effectiveness of 70% (95% CI 59% to 78%), then plateauing.

    “Vaccine effects were noted 10 to 13 days after vaccination, reaching a vaccine effectiveness of 70% (95% confidence interval 59% to 78%), then plateauing.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

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

    Findingown data

    Confidence intervals for the two vaccines overlapped, and further follow-up was needed to understand whether the effects had plateaued for ChAdOx1-S.

    “Confidence intervals for the two vaccines overlapped, and further follow-up was needed to understand whether the effects had plateaued for ChAdOx1-S.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingreasoning

    Notable differences were seen between the adjusted and unadjusted odds ratios in the analysis from 4 January, but this was not seen in the analysis before 4 January.

    “Notable differences were seen between the adjusted and unadjusted odds ratios in this analysis, but this was not seen in the analysis before 4 January.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    For BNT162b2, the odds ratio started to decline 10 to 13 days after vaccination, reaching 0.39 (95% CI 0.31 to 0.49) from 28 days after vaccination, equivalent to a vaccine effectiveness of 61%, then remained at a similar level.

    “For BNT162b2, the odds ratio started to decline 10 to 13 days after vaccination, reaching 0.39 (95% confidence interval 0.31 to 0.49) from 28 days after vaccination, equivalent to a vaccine effectiveness of 61%, then remained at a similar level.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

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

    Findingown data

    Supplementary table 4 shows similar effects in the analysis of ChAdOx1-S including previous individuals with positive test results.

    “Supplementary table 4 shows similar effects in the analysis of ChAdOx1-S including previous individuals with positive test results.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    For ChAdOx1-S, the decline began on days 14 to 20 after vaccination, reaching an odds ratio of 0.40 (0.27 to 0.59) from 28 days after vaccination, equivalent to a vaccine effectiveness of 60%, and then reached 0.27 (0.10 to 0.73) from 35 days after vaccination, equivalent to a vaccine effectiveness of 73% and with wide confidence intervals.

    “For ChAdOx1-S, the decline began on days 14 to 20 after vaccination, reaching an odds ratio of 0.40 (0.27 to 0.59) from 28 days after vaccination, equivalent to a vaccine effectiveness of 60%, and then reached 0.27 (0.10 to 0.73) from 35 days after vaccination, equivalent to a vaccine effectiveness of 73% and with wide confidence intervals.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

  • May combine two claims.

    Findingown data

    In control analysis among those with a negative test result, mortality rates by vaccination status did not differ, indicating no evidence of a healthy vaccinee effect.

    “Mortality rates by vaccination status did not differ in the control analysis among those with a negative test result, indicating no evidence of a healthy vaccinee effect (see supplementary figure 4).”
    • Also stated in: § Results · hedged
      “Mortality rates by vaccination status did not differ in the control analysis among those with a negative test result, indicating no significant evidence of a healthy vaccinee effect (see supplementary figure 6).”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    With other vaccines an extended interval between the prime and booster doses typically provides a better immune response to the booster dose.

    “Furthermore, with other vaccines an extended interval between the prime and booster doses typically provides a better immune response to the booster dose.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites 7 8

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    Week of symptom onset was included in a crude model because the variation in both disease incidence and vaccine delivery in England over the study period meant that an analysis without including time would not be meaningful.

    “Week of symptom onset was included in a crude model because the variation in both disease incidence and vaccine delivery in England over the study period meant that an analysis without including time would not be meaningful.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    A reanalysis of the BNT162b2 trial data suggests that a single dose of this vaccine has an efficacy of 92.6% in the early post-vaccination period.

    “A reanalysis of the BNT162b2 trial data suggests that a single dose of this vaccine has an efficacy of 92.6% in the early post-vaccination period.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [6] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Test negative case-control designs are considered powerful enough to estimate vaccine effectiveness and are used extensively for estimating effectiveness of influenza vaccines and vaccines against other respiratory viruses.

    “Test negative case-control designs are considered powerful enough to estimate vaccine effectiveness and are used extensively for estimating effectiveness of influenza vaccines and vaccines against other respiratory viruses.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites 13 14 15

      Not checked in the free run.

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

    Premisecitation

    Recent analyses suggest that the B.1.1.7 variant has increased transmissibility and has become the dominant strain in large parts of the UK.

    “Recent analyses suggest that this variant has increased transmissibility, and it has since become the dominant strain in large parts of the UK.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites 10 11

      Not checked in the free run.

  • May combine two claims.

    Study design and conductreasoning

    This analysis was restricted to those older than 80 years as this age group was targeted first and follow-up in the 70-79 years age group is still too short to monitor these endpoints.

    “This analysis was restricted to those older than 80 years as this age group was targeted first and follow-up in the 70-79 years age group is still too short to monitor these endpoints.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Several possible confounders were included in the fully adjusted logistic regression model: age, sex, ethnicity, geography, index of multiple deprivation, care home residence, and week of symptom onset.

    “Several possible confounders were included in the fully adjusted logistic regression model: age (in five year age groups, at 31 March 2021), sex, ethnicity, geography (NHS region), index of multiple deprivation, care home residence, and week of symptom onset.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    The B.1.1.7 variant is characterised by 23 mutations, including mutations to genes encoding the spike protein.

    “The variant is characterised by 23 mutations, including mutations to genes encoding the spike protein, the target of the two vaccines currently in use, as well as the majority of vaccine candidates.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] Public Health England. Investigation of novel SARS-COV-2 variant - Variant of Concern 202012/01 2020. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/947048/Technical_Briefing_VOC_SH_NJL2_SH2.pdf

      Not checked in the free run.

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

    Premisecitation

    Interim results from phase III clinical trials have found the BNT162b2 and ChAdOx1-S vaccines to be highly effective when using a two dose schedule with a target interval of three and four weeks, respectively, between doses.

    “Interim results from phase III clinical trials have found the BNT162b2 and ChAdOx1-S vaccines to be highly effective when using a two dose schedule with a target interval of three and four weeks, respectively, between doses.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites 4 5

      Not checked in the free run.

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

    Premisecitation

    Data from the ChAdOx1-S trial suggests that protection might be greater with a longer dosing interval.

    “Data from the ChAdOx1-S trial suggests that protection might be greater with a longer dosing interval.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Stratifying by period indicated that vaccination before 4 January was targeted at those at higher baseline risk of covid-19, whereas from 4 January delivery was more accessible for those with a similar baseline risk to the unvaccinated group.

    “Stratifying by period indicated that vaccination before 4 January was targeted at those at higher baseline risk of covid-19, whereas from 4 January (when ChAdOx1-S was introduced), delivery was more accessible for those with a similar baseline risk to the unvaccinated group.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    We repeated the analysis in people with a negative test result (controls) to assess healthy vaccine bias.

    “We repeated the analysis in people with a negative test result (controls) to assess healthy vaccine bias.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    This effect appears to lessen as the roll-out of the vaccination programme progresses, suggesting that access to vaccines initially focused on those at higher risk.

    “This effect appears to lessen as the roll-out of the vaccination programme progresses, suggesting that access to vaccines initially focused on those at higher risk”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Vaccinated individuals who start to show symptoms have an additional 43% protection against hospital admission within 14 days of a positive covid-19 test result for BNT162b2 and 37% for ChAdOx1-S.

    “indicating that vaccinated individuals who do start to show symptoms have an additional 43% and 37% protection against hospital admission within 14 days of a positive covid-19 test result.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Vaccination can cause systemic reactions, including fever and fatigue, which might prompt more testing for covid-19 in the first few days after vaccination, leading to an artificially low vaccine effectiveness in that period.

    “Vaccination can also cause systemic reactions, including fever and fatigue.23 24 This might prompt more testing for covid-19 in the first few days after vaccination, which, if due to a vaccine reaction, will produce a negative result. This is likely to explain the increased testing immediately after vaccination with ChAdOx1-S and leads to an artificially low vaccine effectiveness in that period.25”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [23] source

      Not checked in the free run.

    • cites [24] Ramsay M. COVID-19: the green book, chapter 14a. Immunisation against infectious diseases: Public Health England. 2020.

      Not checked in the free run.

    • cites [25] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    A single vaccine dose provides additional protection against covid-19 related admissions to hospital and deaths, with vaccinated individuals showing around half the risk of these severe outcomes compared with unvaccinated individuals.

    “We also provide evidence that a single vaccine dose provides additional protection against covid-19 related admissions to hospital and deaths, with vaccinated individuals showing around half the risk of these severe outcomes compared with unvaccinated individuals.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Additional protection against hospital admissions was shown for ChAdOx1-S, suggesting vaccine effectiveness against admission of at least 80% after a single dose.

    “As with BNT162b2, additional protection against hospital admissions was shown, suggesting vaccine effectiveness against admission of at least 80% after a single dose of ChAdOx1-S.”
    Quote in the paperSubstantial claim

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

    Interpretationnone given

    Any misclassification would attenuate vaccine effects.

    “Any misclassification would attenuate vaccine effects.”
    Quote in the paperNot a substantial claim

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

    Interpretationnone given

    The test negative case-control design used in this study may not be suitable in settings where testing is not offered on the basis of symptoms.

    “The test negative case-control design used in our study may also not be suitable in settings where testing is not offered on the basis of symptoms.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Combining the finding of additional protection with the minimum vaccine effectiveness against symptomatic disease estimate suggests that a single dose of BNT162b2 is around 80% effective at preventing hospital admission for covid-19 and around 85% effective at preventing death with covid-19.

    “Combining this finding with our minimum vaccine effectiveness against symptomatic disease estimate would suggest that a single dose of BNT162b2 is around 80% effective at preventing hospital admission for covid-19 and around 85% effective at preventing death with covid-19.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductnone given

    The study had a large sample size, including all community covid-19 testing in England since the start of the vaccination programme, data on symptoms and date of onset, detailed vaccine history, and data on all previous testing.

    “This study has several strengths: the large sample size, including all community covid-19 testing in England since the start of the vaccination programme, data on symptoms and date of onset, detailed vaccine history, and data on all previous testing.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The differences between adjusted and unadjusted odds ratios in the analysis from 4 January were due to confounding by age and care home status, probably because few care home residents were vaccinated in the early period and this period was restricted to a smaller age group (≥80 years).

    “This was due to confounding by age and care home status, probably because few care home residents were vaccinated in the early period and this period was restricted to a smaller age group (≥80 years).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    A single dose of either BNT162b2 or ChAdOx1-S provides significant protection against covid-19 and further protection against severe disease lasting at least six weeks, including against the UK variant of concern (B.1.1.7).

    “A single dose of either BNT162b2 or ChAdOx1-S provides significant protection against covid-19 and further protection against severe disease lasting at least six weeks, including against the UK variant of concern (B.1.1.7)”
    Quote in the paperSubstantial claim
37 of 37

  • The paper relies on this without support.

    Vaccination histories in the National Immunisation Management System are complete and accurate for all covid-19 vaccines administered in England.

    “All covid-19 vaccines administered in England are recorded in NIMS by clinicians through point of care applications.”

  • The paper relies on this without support.

    The B.1.1.7 variant was the dominant virus in England throughout the study period.

    “The B.1.1.7 variant now dominates in the UK and these results will largely reflect vaccine effectiveness against this variant.”
    “In England, the B.1.1.7 variant was the dominant virus throughout the study period.”

  • The paper relies on this without support.

    The typical incubation period of covid-19 is longer than three days.

    “However, the increase occurs within three days, before the typical incubation period of covid-19.”
3 of 3

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?

  • COVID-19 vaccination is a safe and effective measure to prevent the severe progression of COVID-19.

    “Since vaccination is a safe and effective measure to prevent the severe progression of COVID-19 [12-14]”

    From Protective effect of COVID-19 vaccination against long COVID syndrome: A systematic review and meta-analysis (2023) · cites this paper as [12]

    The Discussion reports that vaccination reduced COVID-19-related hospital admissions and deaths among older adults in England. The paper does not assess vaccine safety, so it supports the effectiveness portion of the claim but not the assertion that vaccination is safe. (LLM, conf=0.90)

    Experimental — accuracy not yet measured

  • The two distinct analytic approaches used in the study gave broadly similar results.

    “We used two distinct analytic approaches that gave broadly similar results, and findings with our control analysis (using the alpha variant) are consistent with those that have been reported previously.7,8,10,17”

    From Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant (2021) · cites this paper as [10]

  • The study's control analysis using the alpha variant produced findings consistent with previously reported estimates.

    “We used two distinct analytic approaches that gave broadly similar results, and findings with our control analysis (using the alpha variant) are consistent with those that have been reported previously.7,8,10,17”

    From Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant (2021) · cites this paper as [10]

  • The period from the day of vaccine administration to day 3 was excluded because reactogenicity can increase testing and bias results.

    “The period from the day of vaccine administration (day 0) to day 3 was excluded because reactogenicity to the vaccine can cause an increase in testing that biases results, as previously described.10”

    From Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant (2021) · cites this paper as [10]

  • Covid-19 vaccines are highly effective against symptomatic disease and, more so, against severe disease and fatal outcomes caused by the original strain of SARS-CoV-2 as well as the alpha variant.

    “Coronavirus disease 2019 (Covid-19) vaccines are highly effective against symptomatic disease and, more so, against severe disease and fatal outcomes caused by the original strain of SARS-CoV-2 as well as the alpha (B.1.1.7) variant that predominated in early 2021.”

    From Effectiveness of COVID-19 vaccines against the Omicron (B.1.1.529) variant of concern (2021) · cites this paper as [11]

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.

  • The participant count is a count of samples

    Minor

    The abstract calls 156,930 a count of adults, but the Results identify it as a count of test samples. The paper also says that some people contributed multiple samples, so those counts cannot be interchangeable.

  • An early increased risk is statistically significant in table 3

    Minor

    The text says neither vaccine showed a significantly increased early risk, but table 3 gives BNT162b2 an adjusted odds ratio of 1.13 on days 0-3, with a 95% confidence interval entirely above 1.

  • The stated sample-date restriction excludes most of the study period

    Minor

    Taken literally, including only samples taken from 19 February onward cannot support the stated symptom-onset period beginning 8 December: the Methods also require swabbing within 0-10 days of symptom onset. The date restriction appears to be misstated.

3 of 3

No citation lists for this paper

No citation lists for this paper yet — checked again daily.

References 25 · Cited by 1,389

Research works printed but not linked: 2

  1. Davies NG Barnard RC Jarvis CI . Estimated transmissibility and severity of novel SARS-CoV-2 Variant of Concern 202012/01 in England. medRxiv. 2020:2020.12.24.20248822.
  2. Ramsay M. COVID-19: the green book, chapter 14a. Immunisation against infectious diseases: Public Health England. 2020.

Authors
Lopez Bernal, J., Andrews, N., Gower, C., Robertson, C., Stowe, J., Tessier, E., Simmons, R., Cottrell, S., Roberts, R., O’Doherty, M., Brown, K., Cameron, C., Stockton, D., McMenamin, J., & Ramsay, M.
Affiliations
  • Public Health England (GB)
  • University of Strathclyde (GB)
  • Public Health Wales (GB)
  • Public Health Agency (GB)
  • Health Protection Scotland (GB)
ORCID
Venue
BMJ
Publisher
BMJ
Published
2021-05-13
Volume
373
Pages
n1088
ISSN
1756-1833 (ISSN-L)
DOI
10.1136/bmj.n1088
PMC
PMC8116636
OpenAlex
W3160138987
Cited by
1,389
References
25
Citations by year
2026: 17 · 2025: 74 · 2024: 183 · 2023: 289 · 2022: 481 · 2021: 342 · 2020: 2
FWCI
102.76
Type
journal article
Language
en
Open access
Licence
Locations
  • BMJ (publishedVersion, cc-by-nc)
  • medRxiv (acceptedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • Strathprints: The University of Strathclyde institutional repository (University of Strathclyde) (acceptedVersion)
Funders
Public Health England
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Social Sciences › Health › Vaccine Coverage and Hesitancy
  • Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
Keywords
COVID-19 vaccines, BNT162b2, ChAdOx1 nCoV-19 vaccine, vaccine effectiveness, older adults, SARS-CoV-2, COVID-19 hospitalization, COVID-19 mortality, breakthrough infection, B.1.1.7 variant, community-based testing, test-negative case-control, real-world effectiveness, second dose
MeSH terms
COVID-19, SARS-CoV-2, COVID-19 Vaccines, COVID-19 Testing, BNT162 Vaccine, ChAdOx1 nCoV-19, Aged, Aged, 80 and over, England, Female, Hospitalization, Humans, Male, Vaccination, Case-Control Studies, Treatment Outcome

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.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-06.

Statistics and arithmetic are recomputed, not judged.

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