Pfizer says testing shows booster restores full protection against COVID-19

Pfizer and BioNTech announced on Thursday that a booster shot of their coronavirus vaccine restores full protection against COVID-19.

The companies said that a late-stage clinical trial found that the booster was 95.6 percent effective against symptomatic COVID-19. 

The efficacy results are the first from any randomized, controlled trial of a COVID-19 booster, they said. 


“These results provide further evidence of the benefits of boosters as we aim to keep people well-protected against this disease,” Pfizer CEO Albert Bourla said in a statement.

“We look forward to sharing these data with health authorities and working together to determine how they can be used to support the rollout of booster doses around the world,” he continued.

The trial followed 10,000 individuals ages 16 and older who were given either a booster dose or placebo on average 11 months after completing the initial two doses of the vaccine.

During the study period, only five cases of COVID-19 were seen in the booster group, while 109 were seen in those who had not been given the booster. 

For reference, the companies said in April that a two-dose series was 95.3 percent effective in fighting severe disease six months after the second dose.

The data comes as the U.S. ramps up booster doses of coronavirus vaccine after cases surged due to the delta variant.


Countries like the U.S. and Israel have begun rolling out booster shots. However, the World Health Organization has called for a moratorium on boosters until 2022 to enable every country to vaccinate at least 40 percent of its residents.

The Food and Drug Administration (FDA) authorized booster shots of Pfizer’s vaccine under emergency use in September for people ages 65 and older, as well as for those who are at high risk of severe disease. That dose is to be given at least six months after the second shot. 

On Wednesday, the FDA authorized booster shots of Moderna, also for those age 65 and older or at higher risk of severe disease six months after the second dose. Johnson & Johnson’s booster dose was authorized for everyone 18 and older at least two months after vaccination.

The agency also allowed patients to receive a different booster from the vaccine they initially received.