April 2, 2021 -- Pfizer-BioNTech's BNT162b2 COVID-19 vaccine is 91.3% effective against the virus six days through up to six months after the second dose, according to results from a phase III study where 927 participants exhibited signs of COVID-19. Participants were followed through March 13, 2021.
In the study, 927 patients contracted COVID-19, 850 were in the placebo group, and 77 were in the vaccine group, equating to a 91.3% efficacy rate. However, BNT162b2 is 100% effective against severe disease as defined by the U.S. Centers for Disease Control and Prevention (CDC). Using the U.S. Food and Drug Administration's (FDA) definition of severe COVID-19, the vaccine is 95.3% effective.
In terms of variants, in South Africa where the B.1.351 variant is prevalent, 800 participants were enrolled in the study and nine cases of COVID-19 were observed, all in the placebo group. This indicates the vaccine is 100% effective against the variant.
Regarding safety data, the vaccine demonstrates a favorable safety and tolerability profile as demonstrated in data collected from more than 12,000 vaccinated participants with a follow-up time of at least six months after the second dose.
The data paves the way for Pfizer and BioNTech to submit a biologics license application to the FDA, the firms said.