Reanalysis of Pfizer mRNA BNT162b2 vax data finds no increased efficacy from boost

  

View ORCID ProfileAllan Saul,  View ORCID ProfileHeidi E Drummer,  View ORCID ProfileNick Scott, Tim Spelman, Brendan S Crabb,  View ORCID ProfileMargaret Hellard

doi: https://doi.org/10.1101/2021.02.23.21252315

This article is a preprint and has not been certified by peer review [what does this mean?]. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.

PDF: https://www.medrxiv.org/content/10.1101/2021.02.23.21252315v1.full.pdf\

Abstract

Background In clinical trials two vaccinations with mRNA vaccines have shown high efficacy in preventing COVID-19. However, in the context of a pandemic, the time to generation of protective immunity, the need for and timing of a second vaccination are matters of legitimate debate. This manuscript explores the efficacy and timing of the second dose COVID-19 vaccines, including a reanalysis of data from the Pfizer mRNA BNT162b2 mRNA SARS-CoV-2 vaccine phase 3 study. Methods and findings A non-weighted three-segment, two knot linear regression was fitted to the published cumulative infection incidence from the Pfizer BNT162b2 vaccine Phase III trial using the lspine routine in R. The optimal knot days were estimated through sensitivity analysis and the confidence limits for efficacy estimates were determined by Monte Carlo Simulations. This analysis showed the vaccine was effective from day 11 post first vaccination. The estimated efficacy over the period 11 to 28 days post first vaccination was 0.94 and there was no detectable increase in efficacy following the second vaccination. The efficacy post first vaccination substantially preceded the development of detectable serum neutralizing antibody. Conclusions Strongly protective immunity develops rapidly following a single vaccination and at least in the short period covered by the timetable of the Phase III trial, there was no additional benefit from a second vaccination. This increases options for use of this vaccine, e.g., for ring fence vaccination, for use in travelers and for mass vaccination rollout. It highlights the need for further research into duration of immunity following a single vaccination and for understanding mechanisms of protection.

Competing Interest Statement

NS and MH provide guidance to the Victorian Government COVID-19 response and receive funding from the Victorian Government for the Optimise Study and COVID-19 modelling work. NS received funding from Johnson & Johnson in Jun-Sep 2020 to provide incidence projections for potential vaccine trial sites. BC serves on the Australian National COVID-19 Health Research Advisory Committee that provides guidance to the Australian Federal Government COVID-19 response.

Clinical Trial

re-analysis of published data from NCT04368728

Funding Statement

No external funding

https://www.medrxiv.org/content/10.1101/2021.02.23.21252315v1