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Pfizer's Coronavirus Vaccine Is 52.4% Effective After First Dose

By Cory Renauer - Dec 8, 2020 at 10:06AM

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That conclusion is based on a new, unfiltered look at clinical trial data from the BNT162b2 program.

On Monday morning, the FDA published briefing documents for an upcoming meeting of a panel of independent medical experts who will weigh in on data from the most closely watched vaccine study in the agency's history. This offered the public its first unfiltered look at the clinical trial results that Pfizer ( PFE 1.77% ) and BioNTech ( BNTX -4.91% ) submitted to support their request for emergency use authorization (EUA) for their coronavirus vaccine candidate, BNT162b2, and the biggest reveal so far is a positive one.

A single-dose of BNT162b2 appears effective

You may remember that BNT162b2 leaped over the  50% efficacy bar set by the FDA. Volunteers were shown to be 94.8% less likely to test positive for COVID-19 seven days or longer after receiving their second dose of the vaccine candidate.

According to the briefing document, a total of 121 volunteers tested positive for COVID-19 during the three-week period between their first and second injections. Since 82 of those cases occurred among volunteers randomized to receive a placebo, we can say BNT162b2 is 52.4% effective at preventing COVID-19 following the first dose, with some caveats.

Child getting a vaccine injection.

Image source: Getty Images.

It's important to remember that there wasn't a separate group of patients given just one dose; the vast majority of volunteers received their second injections as planned. Given that, we can't be confident a single dose of BNT162b2 will remain at least 50% effective for more than a few weeks.

This week's reveal won't change plans to distribute BNT162b2 in a two-dose regimen, but it's still terrific news from a public health perspective. The problem of people missing their booster shots has long been a pain point for public health officials.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis – even one of our own – helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.

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Pfizer Inc. Stock Quote
Pfizer Inc.
$54.68 (1.77%) $0.95
BioNTech SE Stock Quote
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