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Efficacy and safety of Pfizer-BioNTech vaccine after six months

The Pfizer-BioNTech (BNT162b2) vaccine prevents COVID-19 effectively for up to six months after the second dose across diverse populations, including 100% efficacy against the Beta variant prevalent in South Africa., found a multinational study.

Although the results were favourable, the study group said their report, published on medRxiv, has several limitations.

Duration of protection and safety data that could be collected in a blinded, placebo-controlled manner were limited by the ethical and practical need to immunise eligible initial placebo recipients under Emergency Use Authorisation, and according to public health authority recommendations. Data presented here do not address whether vaccination prevents asymptomatic infection, but evaluation of that question is ongoing in this study, and real-world data suggest that BNT162b2 (Pfizer-BioNTech) prevents asymptomatic infection.

Preliminary analyses of breakthrough cases have not yet identified a correlate of protection, as vaccine protection rates remain high. This report does not address vaccine efficacy and safety in pregnant women and in children younger than 12 years. Studies evaluating BNT162b2 in these populations are ongoing.

However, the data demonstrate that BNT162b2 prevents COVID-19 effectively for up to six months post-dose 2 across diverse populations, despite the emergence of SARS-CoV-2 variants, including the Beta (B.1.351) lineage, and the vaccine continues to show a favourable safety profile.

Study details

Six Month Safety and Efficacy of the BNT162b2 mRNA COVID-19 Vaccine

Stephen J. Thomas, EdsonD. Moreira Jr., Nicholas Kitchin, Judith Absalon, Alejandra Gurtman, St ephen Lockhart, John L. Perez, Gonzalo Pérez Marc, Fernando P. Polack, Cristiano Zerbini, Ruth Bailey, Kena A. Swanson, Xia Xu, Satrajit Roychoudhury, Kenneth Koury, Salim Bouguermouh, Warren V. Kalina, David Cooper, Robert W. Frenck Jr., Laura L. Hammitt, Özlem Türeci, Haylene Nell, Axel Schaefer, Serhat Ünal, Qi Yang, Paul Liberator, Dina B. Tresnan, Susan Mather, Philip R. Dormitzer, Uğur Şahin, William C. Gruber, Kathrin U. Jansen,

Published in medRxiv on 28 July 2021

BNT162b2 is a lipid nanoparticle-formulated, nucleoside- modified RNA vaccine encoding a prefusion-stabilised, membrane-anchored SARS-CoV-2 full-length spike protein.

It is highly efficacious against COVID-19 and is currently authorised for emergency use or conditional approval worldwide. At the time of authorisation, data beyond two months post-vaccination were unavailable.

In an ongoing, placebo-controlled, observer-blinded, multinational, pivotal efficacy study, 44,165 ≥16-year-old participants and 2,264 12-15-year-old participants were randomized to receive two doses, 21 days apart, of 30 μg BNT162b2 or placebo. Study endpoints reported here are vaccine efficacy (VE) against laboratory-confirmed COVID-19 and safety data, both up to six months post-vaccination.

BNT162b2 continued to be safe and well tolerated. Few participants had adverse events leading to study withdrawal. VE against COVID-19 was 91% (95% CI 89.0-93.2) through up to six months of follow-up, among evaluable participants and irrespective of previous SARS-CoV- 2 infection. VE of 86%-100% was seen across countries and in populations with diverse characteristics of age, sex, race/ethnicity, and COVID-19 risk factors in participants without evidence of previous SARS- CoV-2 infection. VE against severe disease was 97% (95% CI 80.3−99.9). In South Africa, where the SARS-CoV-2 variant of concern, B.1.351 (beta), was predominant, 100% (95% CI 53.5, 100.0) VE was observed.

With up to six months of follow-up and despite a gradually declining trend in vaccine efficacy, BNT162b2 had a favourable safety profile and was highly efficacious in preventing COVID-19.


medRxiv article – Six Month Safety and Efficacy of the BNT162b2 mRNA COVID-19 Vaccine (Open access)
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