Pfizer COVID-19 Vaccine Candidate Achieves 90% Efficacy

November 9, 2020
Grace Halsey
Grace Halsey

Pfizer/BioNTech announced more than 90% efficacy for their vaccine against SARS-CoV-2 infection in the first interim analysis of phase 3 study.

Pfizer/BioNTech announced this morning that their COVID-19 vaccine candidate in joint development is more than 90% effective in preventing COVID-19 in participants without evidence of prior SARS-CoV-2 infection in the first interim efficacy analysis.

The top-line results come from a phase 3 trial of the mRNA-based vaccine candidate, BNT162b2, and an evaluation of 94 cases among the trial's 45 538 patients, according to a Pfizer press release.

The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90%, at 7 days after the second dose, the companies noted.

This means that protection is achieved 28 days after the initiation of the vaccination, which is given on a 2-dose schedule. The companies note that as the study continues, final vaccine efficacy percentage may vary.

No serious safety concerns have been observed, according to the independent safety monitoring committee that conducted this interim analysis.

Currently the companies plan submission to the US Food and Drug Administration (FDA) for Emergency Use Authorization (EUA) after the required safety milestone is reached, an event anticipated in the third week of November.

Executives look ahead

“Today is a great day for science and humanity. 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 Dr Albert Bourla, Pfizer Chairman and CEO.

"...We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks.”

Results will be discussed with regulators worldwide; the European Medicines Agency has already begun its rolling review of data to expedite a decision on the clinical trial dossier.

The phase 3 clinical trial of BNT162b2 began at the end of July and has enrolled 43,538 participants to date; 38 955 of those had received a second vaccine dose as of November 8, 2020. Enrollment of participants of racially and ethnically diverse backgrounds is approximately 42% globally and 30% in the US.

Trial enrollment is expected to continue through final analysis when a total of 164 confirmed COVID-19 cases have accrued. Potential for the vaccine to protect against COVID-19 in those who have had prior exposure to SARS-CoV-2 and against severe COVID-19 disease will be evaluated.

Final study analysis will also evaluate vaccine efficacy based on confirmed cases observed 14 days after the second dose in addition to those from 7 days after. The addition may help align data across all COVID-19 vaccine studies, the companies state in the Pfizer news release. An updated version of the study protocol is now available.

Based on current projections the companies say they expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021.

Pfizer and BioNTech plan to submit data from the full Phase 3 trial for scientific peer-review publication.