New data: Pfizer’s Vaccine Offers Strong Protection After First Dose

WASHINGTON — The coronavirus vaccine made by Pfizer and BioNTech provides strong protection against Covid-19 within about 10 days of the first dose, according to documents published on Tuesday by the Food and Drug Administration before a meeting of its vaccine advisory group.

The finding is one of several significant new results featured in the briefing materials, which include more than 100 pages of data analyses from the agency and from Pfizer. Last month, Pfizer and BioNTech announced that their two-dose vaccine had an efficacy rate of 95 percent after two doses administered three weeks apart. The new analyses show that the protection starts kicking in far earlier.

What’s more, the vaccine worked well regardless of a volunteer’s race, weight or age. While the trial did not find any serious adverse events caused by the vaccine, many participants did experience aches, fevers and other side effects.

On Thursday, F.D.A.’s vaccine advisory panel will discuss these materials in advance of a vote on whether to recommend authorization of Pfizer and BioNTech’s vaccine. ...

The efficacy of the vaccine after the first dose is about 52 percent, according to Dr. William C. Gruber, senior vice president of Pfizer Vaccine Clinical Research and Development. After the second dose, that rises to about 95 percent. “Two doses of vaccine provide maximum protection,” he said. ...