The agency resisted pressure to speed up its process, saying a thorough review was necessary to ensure public confidence.
“While millions of people have already safely received COVID-19 vaccines, we recognize that for some, the FDA approval of a vaccine may now instill additional confidence to get vaccinated. Today’s milestone puts us one step closer to altering the course of this pandemic in the U.S.,” acting FDA Commissioner Janet Woodcock said in a news release.
Experts agreed the move would increase public confidence.
“I don’t expect a big line outside of vaccination sites this afternoon or tomorrow morning, but it will persuade some,” said William Schaffner, MD, a professor of infectious diseases at Vanderbilt University in Nashville.
A recent Kaiser Family Foundation poll found that 3 in 10 unvaccinated adults said they would be more likely to get vaccinated if the vaccines were given full approval.
More importantly, Schaffner said, the FDA’s approval would lay the groundwork for vaccine mandates. “I think those kinds of mandates are going to be necessary to get us up over 80% vaccinated.”
In granting the approval, the agency reviewed a record amount of data from more than 40,000 people who took part in clinical trials. About 12,000 recipients have been followed for at least 6 months, the agency said.
The FDA also reviewed safety data collected since it issued its emergency use authorization for the shots in December.
Based on the results from the clinical trials, the vaccine was 91% effective at preventing COVID-19 disease. But that estimate came from data collected before the Delta variant became widespread.
The most commonly reported side effects in the clinical trials were pain, redness and swelling at the injection site, fatigue, headache, muscle or joint pain, chills, and fever.
The FDA said the vaccine is effective in preventing COVID-19 and potentially serious outcomes, including hospitalization and death.
Based on safety data reviewed since the two-dose vaccine was approved, the FDA said the data demonstrates a higher risk for heart inflammation — clinically known as myocarditis or pericarditis — especially within 7 days after the second dose of the shots. The risk is highest for men under age 40, compared to women and older men.
The prescription information includes warnings about these risks. The FDA said the drugmakers must continue to study the risks and long-term effects on people who have myocarditis after vaccination.