COVID-19 Vaccine Candidate More Than 90% Effective in Phase 3 Study


Pfizer and BioNTech plan for submission to the FDA for an Emergency Use Authorization soon after the required safety milestone is achieved in mid-November for a promising novel COVID-19 vaccine candidate.

Pfizer and BioNTech’s coronavirus disease 2019 (COVID-19) vaccine candidate showed promising results in the first interim analysis from a phase 3 study, showing more than 90% efficacy in preventing COVID-19 among study participants.

The phase 3 clinical trial began in July 2020 and has enrolled more than 43,500 participants. Of those, 38,955 have received a second dose of the vaccine candidate as of November 8, 2020. According to a press release, approximately 42% of the global participants and 30% of the US participants have racially and ethnically diverse backgrounds. The trial is continuing to enroll participants and is expected to continue through the final analysis, according to the press release.

In addition to studying protection for those who have no known exposure to COVID-19, the study will also evaluate the potential protection in those who have had prior exposure, as well as vaccine prevention against severe COVID-19. With FDA approval, the final analysis will also include new secondary endpoints evaluating efficacy based on cases accruing 14 days after the second dose, according to the press release.

“The first set of results from our phase 3 COVID-19 vaccine trial provides the initial evidence of our vaccine’s ability to prevent COVID-19,” said Pfizer Chairman and CEO Albert Bourla, DVM, PhD, in a statement. “We are reaching this critical milestone in our vaccine development program at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity, and economies struggling to reopen.”

The case split between vaccinated participants and those who received the placebo indicates an efficacy rate of more than 90% at 7 days after the second dose, according to a press release. This means that protection is achieved 28 days after initiation of the 2-dose vaccination schedule.

The study authors noted that the final vaccine efficacy percentage may vary as the research continues. No serious safety concerns have been reported.

The investigators currently estimate that a median of 2 months of safety data following the second dose of the vaccine candidate will be available by the third week of November. Participants will continue to be monitored for long-term protection and safety for an additional 2 years after their second dose.

Notably, the press release said submission to the FDA for an Emergency Use Authorization is planned for soon after the required safety milestone is achieved in mid-November.

“Especially today, while we are all in the midst of a second wave and many of us in lockdown, we appreciate even more how important this milestone is on our path toward ending this pandemic and for all of us to regain a sense of normalcy,” said BioNTech co-founder and CEO Ugur Sahin, MD, in a statement. “We will continue to collect further data as the trial continues to enroll for a final analysis planned when a total of 164 confirmed COVID-19 cases have accrued.”


Pfizer and BioNTech Announce Vaccine Candidate Against COVID-19 Achieved Success in First Interim Analysis from Phase 3 Study [news release]. Pfizer; November 9, 2020. Accessed November 9, 2020.

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