CoChat
Sign Up
Cited by 146SARS-CoV-2 and COVID-19 ResearchCOVID-19 Clinical Research StudiesPharmacovigilance and Adverse Drug Reactions

A comprehensive analysis of the efficacy and safety of COVID-19 vaccines

Open access
Cai, Changjing, Peng, Yinghui, Shen, Edward, Huang, Qiaoqiao, Chen, Yihong, Liu, Ping, Guo, Cao, Feng, Ziyang +7 more·2021·Molecular Therapy
DOI 10.1016/j.ymthe.2021.08.001PMC PMC8342868
Open this paper in CoChat — free account

Abstract

The numbers of cases and deaths from coronavirus disease 2019 (COVID-19) are continuously increasing. Many people are concerned about the efficacy and safety of the COVID-19 vaccines. We performed a comprehensive analysis of the published trials of COVID-19 vaccines and the real-world data from the Vaccine Adverse Event Reporting System. Globally, our research found that the efficacy of all vaccines exceeded 70%, and RNA-based vaccines had the highest efficacy of 94.29%; moreover, Black or African American people, young people, and males may experience greater vaccine efficacy. The spectrum of vaccine-related adverse drug reactions (ADRs) is extremely broad, and the most frequent ADRs are pain, fatigue, and headache. Most ADRs are tolerable and are mainly grade 1 or 2 in severity. Some severe ADRs have been identified (thromboembolic events, 21-75 cases per million doses; myocarditis/pericarditis, 2-3 cases per million doses). In summary, vaccines are a powerful tool that can be used to control the COVID-19 pandemic, with high efficacy and tolerable ADRs. In addition, the spectrum of ADRs associated with the vaccines is broad, and most of the reactions appear within a week, although some may be delayed. Therefore, ADRs after vaccination need to be identified and addressed in a timely manner.

AI snapshot

Written from the paper’s full text.

TL;DR

This paper combines meta-analyses of published COVID-19 vaccine trials with real-world Vaccine Adverse Event Reporting System (VAERS) data to assess vaccine efficacy and adverse drug reactions (ADRs). It reports that all vaccines exceeded 70% efficacy, RNA-based vaccines had the highest efficacy at 94.29%, and most ADRs were tolerable grade 1–2 reactions, though rare severe events such as thromboembolic events and myocarditis/pericarditis occurred at low incidence.

Key findings

  • Across phase III trial data including 194,015 cases, vaccine efficacy was 73.11% (95% CI 34.23–89.03) for inactivated vaccines, 89.33% (95% CI 81.44–93.10) for protein subunit vaccines, 94.29% (95% CI 93.65–95.40) for RNA-based vaccines, and 79.56% (95% CI 60.00–89.92) for viral vector (non-replicating) vaccines. Subgroup analyses suggested greater efficacy among Black or African American participants (95.37%), males (92.70%), and those aged 16–55 years (88.89%).
  • In clinical trial meta-analysis, the most frequent ADRs were pain, fatigue, and headache; pain after dose 1 was reported in 80.97% of RNA-based vaccine recipients and 38.46% of protein subunit vaccine recipients, while fatigue after dose 1 was 39.27% for RNA-based and 30.77% for protein subunit vaccines. Most ADRs were grade 1 or 2, and grade ≥3 ADRs were generally less than 10%, with the most frequent being fatigue (6.34%) in RNA-based vaccines after dose 2.
  • Severe rare ADRs included thromboembolic events only in viral vector (non-replicating) vaccines, at 75 cases per million doses for Ad26.COV2.S and 21 cases per million doses for AZD1222, and myocarditis/pericarditis at 2 versus 3 cases per million doses for viral vector versus RNA-based vaccines.
  • In real-world VAERS data including 11,936 participants, headache was the most frequent ADR (16.53%), more than 700 ADRs were identified, and more than 90% of ADRs had an incidence below 1%; most symptoms appeared within a week, with median onset of 2 days for Moderna and 1 day for Pfizer-BioNTech, and the longest interval was 60 days.

Methods

  • The authors performed a meta-analysis of published COVID-19 vaccine trials, including 194,015 cases for efficacy and 56,310 cases for ADR analysis, with subgroup analyses by vaccine type, sex, age, and race where data were available. They also analyzed severe/rare ADRs using 86,506,742 doses for thromboembolic events and 603,862,888 doses for myocarditis/pericarditis events.
  • They retrospectively analyzed real-world VAERS data accessed on March 5, 2021, including 11,936 participants vaccinated with Moderna or Pfizer-BioNTech RNA-based vaccines.
  • Vaccine efficacy was calculated as 1 − relative risk (RR); ADR incidences were compared with χ² tests, and meta-analyses used fixed-effects or random-effects models in R, with descriptive analyses in GraphPad Prism.

Limitations

  • Stated: heterogeneity was large in several subgroups; the authors used five transformation methods, sensitivity analyses, and multiple subgroup analyses to minimize heterogeneity, and did not use Begg’s or Egger’s tests because there were not more than 10 subjects in each group.
  • Stated: VAERS is a self-reporting system with reporting bias and underreporting, lacks standardized symptom descriptions, and real-world data were only available for RNA-based vaccines with a sample size not yet large enough; most clinical trials counted only ADRs occurring within 1 week, potentially omitting delayed reactions.
  • Stated: few mortality cases were reported to VAERS, and there was not enough evidence to indicate that death was related to vaccination; a large-scale real-world study is needed for further confirmation.

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

Integrity signals

Registry

Crossref · 10.1016/j.ymthe.2021.08.001

Cites

26 of 26 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 6 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Subgroup analyses stratified by vaccine type, sex, and age effectively reduced the heterogeneity in vaccine efficacy.

    “we performed subgroup analyses with stratification by vaccine type, sex, and age, which effectively reduced the heterogeneity”
    Quote in the paperSubstantial claim
  • Findingown data

    Among participants in the vaccine efficacy analysis, males had a vaccine efficacy of 92.70% (95% CI 81.00-96.81).

    “Vaccine efficacy (VE) among male and female participants was 92.70% (95% CI, 81.00; 96.81) and 87.84% (95% CI, 75.78; 93.88), respectively.”
    Quote in the paperNot a substantial claim
  • Findingown data

    Males experienced greater vaccine efficacy than females.

    “males may experience greater vaccine efficacy”
    • Also stated in: § Efficacy of COVID-19 vaccines · plain
      “males, and the 16- to-55-year-old subgroup experienced greater VE”
    Quote in the paperSubstantial claim
  • Findingown data

    Participants aged 16 to 55 years had a vaccine efficacy of 88.89% (95% CI 75.45-94.87).

    “the efficacy of vaccine among 16 to 55 years old recipients was 88.89% (95% CI, 75.45; 94.87)”
    Quote in the paperSubstantial claim
  • Findingown data

    Participants over 55 years old had a vaccine efficacy of 87.62% (95% CI 76.83-92.54).

    “that among those over 55 years old was 87.62% (95% CI, 76.83; 92.54)”
    Quote in the paperNot a substantial claim
  • May combine two claims. 30
  • The quote only partly states this claim. 2
  • Classified as probably not a substantial claim. 5

  • May combine two claims.

    Findingown data

    Inactivated COVID-19 vaccines had the lowest efficacy among vaccine types, although they were more than 70% effective.

    “whereas inactivated vaccines had the lowest, although they were more than 70% effective”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Findingown data

    RNA-based COVID-19 vaccines had the highest efficacy among vaccine types, at 94.29% (95% CI 93.65-95.40).

    “RNA-based vaccines had the highest efficacy of 94.29%”
    • Also stated in: § Efficacy of COVID-19 vaccines · plain
      “the efficacy of RNA-based vaccines was 94.29% (95% CI, 93.65; 95.40)”
    • Also stated in: § Abstract · plain
      “RNA-based vaccines had the highest”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Most ADRs of COVID-19 vaccines are tolerable and are mainly grade 1 or 2 in severity.

    “Most ADRs are tolerable and are mainly grade 1 or 2 in severity.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The incidence of pain after dose 2 was 31.75% for inactivated vaccines, 57.69% for protein subunit vaccines, 81.76% for RNA-based vaccines, and 44.75% for viral vector (non-replicating) vaccines.

    “The incidences of pain in patients administered different types of vaccines were as follows: inactivated vaccines (31.75%), protein subunit vaccines (57.69%), RNA-based vaccines (81.76%), and viral vector (non-replicating) vaccines (44.75%).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Among participants who received the first dose of an RNA-based vaccine, grade 4 fever was noted, but the proportion was less than 5%.

    “Importantly, among the participants who received the first dose of an RNA-based vaccine, grade 4 fever was noted, but the proportion was less than 5%.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    For the other three types of vaccines, ADRs after dose 2 were similar to those after dose 1, with fatigue and headache ranking second and third, respectively.

    “The ADRs associated with the other three types of vaccines were similar to those after dose 1, with fatigue and headache ranking second and third, respectively.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The incidence of ADRs was lowest for inactivated vaccines, with incidences of all ADRs less than 10%.

    “In particular, the incidence of ADRs was lowest for inactivated vaccines, with incidences of all ADRs less than 10%.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In the analysis of ADRs over grade 3, the incidences were all less than 10%, and the most frequently reported ADR was fatigue (6.34%) in RNA-based vaccines after dose 2.

    “In the analysis of ADRs over grade 3, the incidences were all less than 10%, among which the most frequently reported ADR was fatigue (6.34%) in RNA-based vaccines after dose 2.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Most ADRs after COVID-19 vaccination appear within a week, although some may be delayed.

    “most of the reactions appear within a week, although some may be delayed”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The incidence of pain after dose 2 was 72.40% in the 16- to 55-year-old group and 51.06% in the over-55-year-old group.

    “The incidences of pain in different age groups were as follows: 16 to 55 years old (72.40%) and over 55 years old (51.06%).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The ADRs associated with the RNA-based vaccine (Moderna, BNT162b2) were the most severe, and instances of grade 3 reactions were reported for all 8 ADRs.

    “The results showed that the ADRs associated with the RNA-based vaccine (Moderna, BNT162b2) were the most severe, and instances of grade 3 reactions were reported for all 8 ADRs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Among ADRs with incidences less than 50%, chills ranked fifth after dose 2, while it had ranked sixth after dose 1; the other ADRs in order were joint pain (arthralgia), swelling, and fever.

    “Moreover, among the other ADRs with incidences less than 50%, chills ranked fifth after dose 2, while it had ranked sixth after dose 1, and the other ADRs in order were joint pain (arthralgia), swelling, and fever.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    More than 50% of recipients experienced headache after dose 2, unlike after dose 1.

    “However, more than 50% of recipients experienced headache after dose 2, unlike after dose 1.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Grade 3 ADRs also occurred after vaccination with viral vector (non-replicating) vaccines (AZD1222, Sputnik V), but the proportions were low (less than 10%).

    “Grade 3 ADRs also occurred after vaccination with viral vector (non-replicating) vaccines (AZD1222, Sputnik V); however, the proportions were low (less than 10%).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The ADR grades were higher after the second dose than the first dose in RNA-based vaccines, contrary to the viral vector (non-replicating) vaccines (AZD1222, Sputnik V).

    “The ADR grades were higher after the second dose than the first dose in RNA-based vaccines, contrary to the viral vector (non-replicating) vaccines (AZD1222, Sputnik V).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

    Findingnone given

    Many people recover without any medication.

    “many people recover without any medication.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The median symptom onset interval was 1 day in females and 2 days in males.

    “Symptoms appeared earlier in females, with a median interval of 1 day, while in males it was 2 days”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    More than 700 ADRs were identified in the real-world VAERS analysis, but the incidence of most ADRs (more than 90%) was lower than 1%.

    “We identified more than 700 ADRs, but the incidence of most ADRs (more than 90%) was lower than 1% (Figure 3D).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: VAERS reports can be used to estimate the incidence of ADRs in the real world.

  • May combine two claims.

    Findingown data

    The median symptom onset interval was 1 day in young participants and 2 days in older participants.

    “Symptoms appeared earlier in young participants, and the median interval was 1 day, while in older people, it was 2 days”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    Young people, Black or African American people, and males may experience greater vaccine efficacy.

    “young people, Black or African American people, and males may experience greater vaccine efficacy.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    For the Pfizer-BioNTech vaccine, ADRs were reported more often in young participants than in older participants (opposite of Moderna).

    “The result was the opposite for the Pfizer-BioNTech vaccine”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The median symptom onset time was 2 days for the Moderna vaccine and 1 day for the Pfizer-BioNTech vaccine.

    “The median symptom onset time for the Moderna and Pfizer-BioNTech vaccines were 2 days and 1 day, respectively”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Except for pyrexia and chills, which were more common in males, the incidences of other ADRs were higher in females than in males.

    “Other than pyrexia and chills, which were more common in males, the incidences of other ADRs were higher in females than in males”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    The incidences of thromboembolic events and myocarditis/pericarditis events after viral vector vaccines were low.

    “the incidences of thromboembolic events and myocarditis/pericarditis events were low.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    A total of 12 clinical trials were assessed individually, and 194,015 cases were included.

    “Finally, 12 clinical trials were assessed individually, and a total of 194,015 cases were included.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    Thromboembolic events and myocarditis/pericarditis events have been reported after vaccination with viral vector (non-replicating) vaccines (Ad26.COV2.S and AZD1222).

    “some thromboembolic events and myocarditis/pericarditis events have been reported after vaccination with viral vector (non-replicating) vaccines (Ad26.COV2.S and AZD1222)”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    A total of 86,506,742 doses with thromboembolic events and 603,862,888 doses with myocarditis/pericarditis events were included.

    “a total of 86,506,742 doses with thromboembolic events and 603,862,888 doses with myocarditis/pericarditis events were included.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    COVID-19 vaccines are a powerful tool that can be used to control the COVID-19 pandemic, with high efficacy and tolerable ADRs.

    “In summary, vaccines are a powerful tool that can be used to control the COVID-19 pandemic, with high efficacy and tolerable ADRs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductown data

    Inactivated vaccines and protein subunit vaccines lacked subgroup data including age and sex, so only RNA-based and viral vector vaccines were included in subsequent subgroup analyses.

    “Since inactivated vaccines and protein subunit vaccines lacked subgroup data, including age and sex, only RNA-based vaccines and viral vector (non-replicating) vaccines were included in the subsequent subgroup analyses.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    Healthcare providers, vaccine manufacturers, and the public can submit reports to VAERS.

    “Healthcare providers, vaccine manufacturers, and the public can submit reports to the system.6”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] Chen, 1994, The Vaccine Adverse Event Reporting System (VAERS), Vaccine source

      Not checked in the free run.

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

    Study design and conductown data

    The Begg's and Egger's tests were not used because there were not more than 10 subjects in each group.

    “The Begg’s and Egger’s tests were not used because there were not more than 10 subjects in each group.15”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [15] Sterne, 2011, Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomised controlled trials, BMJ source

      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 registered in PROSPERO (CRD42021234481).

    “The study was registered in PROSPERO (CRD42021234481).”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    VAERS is comanaged by the CDC and the FDA and has been used to detect possible safety problems in U.S.-licensed vaccines since 1990.

    “The VAERS is comanaged by the CDC and the FDA and has been used to detect possible safety problems in U.S.-licensed vaccines since 1990.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] Chen, 1994, The Vaccine Adverse Event Reporting System (VAERS), Vaccine source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The VAERS is a self-reporting system with reporting bias.

    “the VAERS is a self-reporting system with reporting bias,10”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [10] Goodman, 2006, Vaccine adverse event reporting system reporting source: a possible source of bias in longitudinal studies, Pediatrics source

      Not checked in the free run.

34 of 34

  • The paper relies on this without support.

    Many people are concerned about the safety and efficacy of the COVID-19 vaccines, and this is one of the key reasons for the low vaccination rate.

    “One of the key reasons for the low vaccination rate is that many people are concerned about the safety and efficacy of the COVID-19 vaccines.”

  • The paper relies on this without support.

    No reports have addressed the safety and efficacy of COVID-19 vaccines satisfactorily.

    “However, no reports have addressed this issue satisfactorily.”

  • The paper relies on this without support.

    Only vaccines can stop the spread of the COVID-19 pandemic.

    “There is no cure for COVID-19, and only vaccines can stop the spread of the COVID-19 pandemic.”

  • The paper relies on this without support.

    Vaccination can reduce the severity of COVID-19 infection and be life saving.

    “Other than protection, vaccination can reduce the severity of COVID-19 infection and be life saving.”

  • The paper relies on this without support.

    Herd immunity is becoming unrealistic unless a vaccine to protect against different variants of SARS-CoV-2 can be developed.

    “as various mutations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported, herd immunity is becoming more and more unrealistic, unless a vaccine to protect against different variants of SARS-CoV-2 can be developed”

  • The paper relies on this without support.

    VAERS reports can be used to estimate the incidence of ADRs in the real world.

    “we retrospectively obtained real-world data from the Vaccine Adverse Event Reporting System (VAERS)”
    “The incidence of ADRs in the real world was far lower than that in clinical trials.”

  • The paper relies on this without support.

    In most clinical trials, only ADRs that occurred within 1 week were counted, and those that appeared after 1 week were omitted.

    “only ADRs that occurred within 1 week were counted in most clinical trials, and those that appeared after 1 week were omitted.”

  • The paper relies on this without support.

    The VAERS system lacks a standardized description of symptoms, with multiple different descriptions referring to the same ADR, falsely increasing the spectrum of ADRs.

    “the VAERS system lacks a standardized description of symptoms, with multiple different descriptions referring to the same ADR, falsely increasing the spectrum of ADRs.”

  • The paper relies on this without support.

    A large number of participants who were vaccinated did not report their ADRs, resulting in a lower incidence rate than in clinical trials.

    “a large number of participants who were vaccinated did not report their ADRs, resulting in a lower incidence rate than in clinical trials.”

  • The paper relies on this without support.

    The process of building tolerance to viral vector (non-replicating) vaccines is gradual in vaccinated recipients.

    “The process of building tolerance to viral vector (non-replicating) vaccines is gradual in vaccinated recipients.”
10 of 10

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?

  • Neither myocarditis nor pericarditis was observed, a finding consistent with the low frequency of these adverse events with real-world use of BNT162b2 in other age groups.

    “Neither myocarditis nor pericarditis was observed, a finding consistent with the low frequency of these adverse events with real-world use of BNT162b2 in other age groups.32”

    From Evaluation of the BNT162b2 Covid-19 Vaccine in Children 5 to 11 Years of Age (2022) · cites this paper as [32]

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.

  • Grade 3 chills reported despite zero total chills

    Minor

    For protein subunit vaccines after dose 2, Table 2 reports a chills incidence of 0.0000 but a grade 3-or-higher chills incidence of 0.0189. The severe cases cannot exceed all cases for the same 26 recipients.

1 of 1

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Related

Authors
Cai, C., Peng, Y., Shen, E., Huang, Q., Chen, Y., Liu, P., Guo, C., Feng, Z., Gao, L., Zhang, X., Gao, Y., Liu, Y., Han, Y., Zeng, S., & Shen, H.
Affiliations
  • Central South University (CN)
  • McMaster University (CA)
Corresponding author
  • Han, Ying
  • Zeng, Shan
  • Shen, Hong
ORCID
Venue
Molecular Therapy
Publisher
Elsevier BV
Published
2021-09
Volume
29
Issue
9
Pages
2794-2805
ISSN
1525-0016 (ISSN-L)
DOI
10.1016/j.ymthe.2021.08.001
PMC
PMC8342868
OpenAlex
W3190889496
Cited by
146
References
26
Citations by year
2026: 2 · 2025: 10 · 2024: 20 · 2023: 46 · 2022: 58 · 2021: 9
FWCI
3.89
Type
journal article
Language
en
Open access
Licence
Locations
  • Molecular Therapy (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Natural Science Foundation of China (81172470, 81772627, 81372629, 81974384, 81874073, 81070362)
  • Fundamental Research Funds for Central Universities of the Central South University (2019zzts797, 2020zzts273)
  • National Key Research and Development Program of China (2018YFC1313300)
  • Natural Science Foundation of Hunan Province (2015JC3021, 2016JC2037)
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Pharmacovigilance and Adverse Drug Reactions
Keywords
COVID-19 vaccines, vaccine efficacy, vaccine safety, adverse drug reactions, RNA vaccines, thromboembolic events, myocarditis, pericarditis, real-world data, VAERS
MeSH terms
Immunogenicity, Vaccine, COVID-19, SARS-CoV-2, COVID-19 Vaccines, mRNA Vaccines, Adolescent, Adult, Aged, Aged, 80 and over, Black or African American, Female, Humans, Male, Middle Aged, Retrospective Studies, Vaccination, Vaccines, Synthetic, Incidence, Treatment Outcome, Clinical Trials, Phase III as Topic, Black People, White People, Young Adult, Pandemics

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 2026-10-10.

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

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review