Outcome Reporting Bias in COVID-19 mRNA Vaccine Clinical Trials
Open accessAbstract
Relative risk reduction and absolute risk reduction measures in the evaluation of clinical trial data are poorly understood by health professionals and the public. The absence of reported absolute risk reduction in COVID-19 vaccine clinical trials can lead to outcome reporting bias that affects the interpretation of vaccine efficacy. The present article uses clinical epidemiologic tools to critically appraise reports of efficacy in Pfzier/BioNTech and Moderna COVID-19 mRNA vaccine clinical trials. Based on data reported by the manufacturer for Pfzier/BioNTech vaccine BNT162b2, this critical appraisal shows: relative risk reduction, 95.1%; 95% CI, 90.0% to 97.6%; p = 0.016; absolute risk reduction, 0.7%; 95% CI, 0.59% to 0.83%; p < 0.000. For the Moderna vaccine mRNA-1273, the appraisal shows: relative risk reduction, 94.1%; 95% CI, 89.1% to 96.8%; p = 0.004; absolute risk reduction, 1.1%; 95% CI, 0.97% to 1.32%; p < 0.000. Unreported absolute risk reduction measures of 0.7% and 1.1% for the Pfzier/BioNTech and Moderna vaccines, respectively, are very much lower than the reported relative risk reduction measures. Reporting absolute risk reduction measures is essential to prevent outcome reporting bias in evaluation of COVID-19 vaccine efficacy.
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The Moderna mRNA-1273 COVID-19 vaccine trial had approximately 5% relative risk, 95% relative risk reduction, and 1.1% absolute risk reduction.
“Mrna-1273: 0.07% vaccine infection rate / 1.2% placebo infection rate = 5% RR, 95% RRR, 1.1% ARR”
From Relative risk reduction: Misinformative measure in clinical trials and COVID-19 vaccine efficacy (2022) · cites this paper as [3]
The Pfizer/BioNTech BNT162b2 COVID-19 vaccine trial had approximately 5% relative risk, 95% relative risk reduction, and 0.7% absolute risk reduction.
“BNT162b2: 0.04% vaccine infection rate / 0.75% placebo infection rate = 5% RR, 95% RRR, 0.7% ARR”
From Relative risk reduction: Misinformative measure in clinical trials and COVID-19 vaccine efficacy (2022) · cites this paper as [3]
Misinterpreting the relative risk reduction can cause reported results to appear very much larger than the absolute risk reduction, as occurred in the clinical trial reports for the COVID-19 mRNA vaccines.
“Misinterpreting the RRR can cause the reported results to appear very much larger than the ARR, as occurred in the clinical trial reports for the COVID-19 mRNA vaccines [3].”
From Relative risk reduction: Misinformative measure in clinical trials and COVID-19 vaccine efficacy (2022) · cites this paper as [3]
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References 22 · Cited by 44
Research works printed but not linked: 4
- [17]Dasgupta S. A Review of Vaccine Efficacy Measures Vaccin Res. Open J. 2019 1 61 64
- [18]Irwig L. Irwig J. Revena L. Sweet M. Relative risk, relative and absolute risk reduction, number needed to treat and confidence intervals Smart Health Choices: Making Sense of Health Advice Hammersmith Press London, UK 2008 Chapter 18 22013602
- [31]Shah P. Thornton I. Turrin D. Hipskind J.E. Informed Consent Available online: https://www.ncbi.nlm.nih.gov/books/NBK430827/#:~:text=Informed%20consent%20is%20the%20process,undergo%20the%20procedure%20or%20intervention (accessed on 8 February 2021)
- [32]Demicheli V. Jefferson T. Ferroni E. Rivetti A. Di Pietrantonj C. Vaccines for preventing influenza in healthy adults Cochrane Database Of Systematic Reviews Cochrane Library Hoboken, NJ, USA 2018 Available online: https://pubmed.ncbi.nlm.nih.gov/29388196 (accessed on 7 January 2021) PMC6491184 29388196
- Authors
- Brown, R. B.
- Affiliations
- University of Waterloo (CA)
- Corresponding author
- Brown, Ronald B.
- ORCID
- Brown, Ronald B.
- Venue
- Medicina
- Publisher
- MDPI AG
- Published
- 2021-02-26
- Volume
- 57
- Issue
- 3
- Pages
- 199
- ISSN
- 1010-660X (ISSN-L)
- 1648-9144
- PMC
- PMC7996517
- OpenAlex
- W3129539821
- Cited by
- 44
- References
- 22
- Citations by year
- 2026: 2 · 2025: 3 · 2024: 6 · 2023: 11 · 2022: 14 · 2021: 8
- FWCI
- 3.09
- Type
- journal article
- Language
- en
- Open access
- gold
- dx.doi.org
- Licence
- Locations
- Medicina (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Funders
- University of Waterloo
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Keywords
- selective reporting, COVID-19 mRNA vaccine, vaccine efficacy, absolute risk reduction, relative risk reduction, BNT162b2, mRNA-1273, clinical trial reporting
- MeSH terms
- COVID-19, SARS-CoV-2, COVID-19 Vaccines, BNT162 Vaccine, 2019-nCoV Vaccine mRNA-1273, Clinical Trials as Topic, Humans, Risk, RNA, Viral, Bias, Treatment Outcome, Numbers Needed To Treat
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