Efficacy reporting of the BNT162b2 mRNA Covid-19 Vaccine trial (Preprint) S. Mickenautsch1 V.W. Berger2

1Review Center For Health Science Research, 84 Concorde Road East, Bedfordview/Johannesburg, 2008, South Africa 2Biometry Research Group, National Cancer Institute, 9609 Medical Center Drive, Rockville, MD 20850, USA

The BNT162b2 mRNA vaccine trial reported a 95% COVID-19 preventive effect (95% credible interval, 90.3 - 97.6).1 However, although random assignment was reported, neither the trial report nor the protocol specified how the random allocation sequence was generated, and this calls the allocation concealment into question too. Even granted that generation of the random sequence was appropriate, lack of information concerning allocation concealment leads to the assumption that such was done inadequately. Trials using inadequate allocation concealment are associated with 37% increased average estimate of benefit.2 If such was the case with the BNT162b2 trial then the true preventive effect may be considerably less than e.g. the 90% of a two-dose polio-vaccination.3 In line with the CONSORT statement,4 it will be helpful if the authors provide sufficient information about the methods how the random allocation sequence was generated and how its concealment implemented. Such information will assist independent trial appraisal to establish the validity of the reported vaccine efficacy, thus preventing the assumption that the apparent effect was due to bias.

Declaration of financial interests The authors declare to have no potential conflict of interest relevant to this letter. References 1. Polack FP, Thomas SJ, Kitchin N, Absalon J, Gurtman A, Lockhart S, Perez JL, Pérez Marc G, Moreira ED, Zerbini C, Bailey R, Swanson KA, Roychoudhury S, Koury K, Li P, Kalina WV, Cooper D, Frenck RW Jr, Hammitt LL, Türeci Ö, Nell H, Schaefer A, Ünal S, Tresnan DB, Mather S, Dormitzer PR, Şahin U, Jansen KU, Gruber WC; C4591001 Clinical Trial Group. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. N Engl J Med 2020;383:2603-2615. 2. Moher D, Cook DJ, Jadad AR, Tugwell P, Moher M, Jones A, Pham B, Klassen TP. Assessing the quality of reports of randomised trials: implications for the conduct of meta-analyses. Health Technol Assess 1999;3:i-iv, 1-98. 3. Centers for Disease Control and Prevention (CDC). Polio Vaccine Effectiveness and Duration of Protection. Website: https://www.cdc.gov/vaccines/vpd/polio/hcp/effectiveness-duration-protection.html (Accessed: January 03, 2021). 4. Moher D, Schulz KF, Altman DG. The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomised trials. Lancet 2001;357:1191-4.