In Phase 3 studies, both the Pfizer-BioNTech and Moderna vaccines were found to be 95% effective in the early months after the vaccine. Put simply, “If there were 100 people who would have gotten COVID, it prevented 95 of them from getting it, but it didn’t prevent all 100,” says Dr. Marks. “It definitely provides some protection, but it’s not perfect.”
The good news is that early data found that those who did contract COVID-19 after receiving the vaccine did not develop a severe form of the disease. “So even if it doesn’t completely prevent illness, the study data shows that it does reduce the severity,” says Dr. Marks.
The third vaccine authorized in the United States also provides strong protection against severe illness and death. This vaccine, made by Johnson & Johnson, reported a 72% efficacy rate in preventing moderate to severe disease from COVID-19 in the U.S. and was 85 percent effective in preventing severe disease. Among the people who received the vaccine during clinical trials, after 28 days no one who contracted COVID-19 was hospitalized or died.