Pfizer's vaccine offers strong protection after first dose

New analyses of Pfizer and BioNTech's coronavirus vaccine indicate strong protection against COVID-19 within about 10 days of the first dose, much sooner than initially thought. Efficacy is about 52% with the first dose, then reaches about 95% with the second, the evidence shows.

New analyses of Pfizer and BioNTech's coronavirus vaccine indicate strong protection against COVID-19 within about 10 days of the first dose, much sooner than initially thought. Efficacy is about 52% with the first dose, then reaches about 95% with the second, the evidence shows. Additionally, the vaccine appears to work well regardless of race, weight, or age. Although FDA found no "meaningful imbalances" in serious health complications between trial volunteers who received the vaccine and those who received a placebo, the new analysis notes that many vaccine recipients felt ill for a day or two after receiving the second dose. FDA published these and other updates as part of briefing materials for Thursday's scheduled meeting of the agency's vaccine advisory group. After reviewing the evidence, the panel will vote on whether to recommend authorization of the vaccine. Even if approved, though, the large-scale clinical trial will go on. Pfizer and BioNTech have said they will encourage volunteers to stick with the study as long as possible so that investigators can collect as much information as possible on safety and efficacy.