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. In November, 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.