Pfizer has been working with BioNTech on a vaccine for COVID-19, and their early analysis suggests their vaccine candidate is over 90% effective. That would be a much higher than expected rate of efficacy from one of the earliest vaccine candidates for the virus. The U.S. Food and Drug Administration is looking for at least 50% efficacy from a COVID-19 vaccine.
Pfizer vaccine may be very effective
The interim analysis focused on the first 94 confirmed cases of COVID-19 among the over 43,000 volunteers who received either two doses of the vaccine or a placebo. The analysis found that fewer than 10% of the infections were in volunteers who had received the vaccine. More than 90% of the cases of COVID-19 were in people who got the placebo.
Pfizer also said its COVID-19 vaccine had an efficacy rate higher than 90% at seven days following the second dose. That means the vaccine starts protecting against the virus 28 days after vaccination begins. It requires two doses.
Pfizer plans to seek emergency use authorization from the FDA quickly after volunteers who received the vaccine have been watched for two months after their second dose. The drug maker expects to reach that milestone by the third week of this month.
How vaccination works
Dr. Anthony Fauci told CNN that Pfizer's results are "extraordinarily good news." Fauci added that he hasn't seen the vaccine data himself, but he spoke to Pfizer CEO Albert Bourla last night.
More results from study of the vaccine will be forthcoming. The Phase 3 trial of the Pfizer COVID-19 vaccine has enrolled more than 43,000 volunteers since July. As of Sunday, almost 39,000 of those volunteers received a second dose of the vaccine. The end goal of the trial is to hit 164 confirmed cases of infection with COVID-19.
Pfizer's vaccine uses a new technology called messenger RNA, which hasn't ever been approved before. It produces an immune response in those who receive it. The mRNA approach tricks cells into producing protein that looks like bits of the virus. The immune system then learns to recognize and attack those pieces in what would theoretically be a quick reaction to a real infection.
So far, the vaccine hasn't demonstrated any reasons for safety concerns. It's unclear just how long Pfizer's vaccine will protect against COVID-19. It's possible that annual shots will be necessary.