Pfizer’s mRNA vaccine 95% efficacious, final analysis shows

On November 18, Pfizer announced that the final efficacy analysis of its candidate mRNA-based vaccine (BNT162b2) in phase-3 trial has been completed and the vaccine shows 95% efficacy to prevent COVID-19 disease beginning 28 days after the first dose.

On November 18, Pfizer announced that the final efficacy analysis of its candidate mRNA-based vaccine (BNT162b2) in phase-3 trial has been completed and the vaccine shows 95% efficacy to prevent COVID-19 disease beginning 28 days after the first dose. Efficacy has been found to be consistent across age, gender, race and ethnicity demographics.

Safety data required by U.S. FDA for Emergency Use Authorization (EUA) has also been achieved, Pfizer announced.

The company plan to submit data to FDA for Emergency use Authorisation “within days” and also share data with regulatory agencies in other countries. The trial will continue to collect efficacy and safety data in participants for an additional two years.

The efficacy data is based on 170 confirmed cases of COVID-19, of which 162 are in the placebo group while eight are in the vaccine group. While the first preliminary analysis announced on November 9 did not reveal whether the vaccine was effective in preventing disease in older adults, the November 18 release says the vaccine has been 94% effective in preventing COVID-19 disease in adults over 65 years of age.

Of the over 41,000 participants who received two doses of the vaccine as on November 13, 41% of participants in Germany, Turkey, South Africa, Brazil and Argentina and 45% of U.S. participants are 56-85 years of age.

If the company did not reveal whether the vaccine was effective in preventing severe COVID-19 disease at the time of the first interim analysis, the company now says the vaccine has been effective in preventing severe disease. Of the 10 severe cases of COVID-19 observed in the trial, nine participants were in the placebo group and just one participant in the vaccine arm.

Safety data

Safety data of a randomised subset of at least 8,000 participants 18 years and older in the Phase-2/3 study demonstrates that the vaccine is “well tolerated”, the release says. According to STAT news, nearly 19,000 participants in the study have been followed for at least two months since their second dose of the vaccine.

Most of the adverse events were transient and resolved shortly after vaccination. The most common adverse effects observed in more than 2% of the participants were fatigue (3.8%) and headache (2%). Pfizers says older adults tended to report “fewer and milder” adverse events following vaccination.

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