Pfizer and BioNTech have announced updated top-line results from analysis of 927 confirmed symptomatic cases of COVID-19 observed in their pivotal Phase 3 study through 13 March, 2021, showing the Pfizer-BioNTech COVID-19 vaccine, BNT162b2, was 91.3% effective against COVID-19, measured seven days through up to six months after the second dose. The vaccine was 100% effective against severe disease as defined by the US Centres for Disease Control and Prevention (CDC), and 95.3% effective against severe COVID-19 as defined by the US Food and Drug Administration (FDA).
Safety data from the Phase 3 study has also been collected from more than 12,000 vaccinated participants who have a follow-up time of at least six months after the second dose, demonstrating a favourable safety and tolerability profile.
“These data confirm the favourable efficacy and safety profile of our vaccine and position us to submit a Biologics License Application to the US FDA,” said Albert Bourla, chair and CEO, Pfizer. “The high vaccine efficacy observed through up to six months following a second dose and against the variant prevalent in South Africa provides further confidence in our vaccine’s overall effectiveness.”
“It is an important step to further confirm the strong efficacy and good safety data we have seen so far, especially in a longer-term follow-up,” said Ugur Sahin, CEO and co-founder of BioNTech. “These data also provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population.”
The updated analysis of the Phase 3 clinical trial was conducted in accordance with guidance from the FDA for all companies investigating COVID-19 vaccines to review safety and efficacy at key milestones.
Results from this analysis of 46,307 trial participants build upon and confirm previously released data and demonstrate strong protection against COVID-19 through six months post-second dose. From the 927 confirmed symptomatic cases of COVID-19 in the trial, 850 cases of COVID-19 were in the placebo group and 77 cases were in the BNT162b2 group, corresponding to vaccine efficacy of 91.3% (95% confidence interval [CI, 89.0, 93.2]).
Thirty-two cases of severe disease, as defined by the CDC, were observed in the placebo group versus none in the BNT162b2 vaccinated group, indicating that the vaccine was 100% efficacious in this analysis against severe disease by the CDC definition (95% CI, [88.0,100.0]). Twenty-one severe cases, as defined by the FDA, were observed in the placebo group versus one case in the BNT162b2 vaccinated group, indicating 95.3% efficacy by the FDA definition (95% CI, [71.0, 99.9]).
Efficacy was generally consistent across age, gender, race and ethnicity demographics, and across participants with a variety of underlying conditions.
A total of 697 cases of COVID-19 were observed in the US; 647 cases of COVID-19 were observed in the placebo group versus 50 in the vaccine group, indicating vaccine efficacy of 92.6% (95% CI, [90.1, 94.5]).
In South Africa, where the B.1.351 lineage is prevalent and 800 participants were enrolled, nine cases of COVID-19 were observed, all in the placebo group, indicating vaccine efficacy of 100% (95% CI, [53.5, 100.0]). In an exploratory analysis, the nine strains were sequenced and six of the nine were confirmed to be of the B.1.351 lineage. These data support previous results from immunogenicity studies demonstrating that BNT162b2 induced a robust neutralising antibody response to the B1.351 variant, and although lower than to the wild-type strain, it does not appear to affect the high observed efficacy against this variant.
No serious safety concerns were observed in trial participants up to six months after the second dose. Side effects were generally consistent with previously reported results. Vaccine safety has now been evaluated in more than 44,000 participants aged 16 years and older with more than 12,000 vaccinated participants having at least six months of follow-up after their second dose.
Pfizer and BioNTech plan to submit detailed data for scientific peer review and potential publication in the near future.