(CNN) A booster dose of the Pfizer/BioNTech coronavirus vaccine was found to have a high efficacy -- 95.6% -- against Covid-19 in a Phase 3 trial, the companies announced on Thursday. They noted that "efficacy was consistent irrespective of age, sex, race, ethnicity or comorbid conditions."
The trial included more than 10,000 fully vaccinated people, age 16 and older, who randomly received either the 30-microgram booster dose of vaccine or a placebo. The median time between completing their initial second dose of vaccine and receiving a booster or placebo was about 11 months, the companies said.
Pfizer and BioNTech reported that during the study, there were 109 Covid-19 cases among people who received a placebo and five cases among those who received the third dose of vaccine. The companies noted that the vaccine efficacy they found, of 95.6%, reflects that reduction of disease among those who received a booster shot versus those who did not. These are the first results from a randomized, controlled Covid-19 vaccine booster trial, the companies said, and they reflect a period when the highly contagious Delta variant was prevalent.
"These results provide further evidence of the benefits of boosters as we aim to keep people well-protected against this disease," Albert Bourla, Pfizer's chairman and chief executive officer, said in a news release Thursday.
"In addition to our efforts to increase global access and uptake among the unvaccinated, we believe boosters have a critical role to play in addressing the ongoing public health threat of this pandemic," Bourla said. "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."
In September, the US Food and Drug Administration authorized a booster dose of the Pfizer/BioNtech coronavirus vaccine for emergency use in adults 65 and older, adults at high risk of severe Covid-19 and adults with frequent exposure to the coronavirus through their work.
Then on Wednesday, the FDA authorized the Pfizer/BioNTech booster for those who may be eligible but are fully vaccinated with either the Moderna or Johnson & Johnson coronavirus vaccines, as a mix-and-match approach.
Now, the US Centers for Disease Control and Prevention's vaccine advisers, the Advisory Committee on Immunization Practices, meet Thursday to decide on whether to recommend the FDA's recent mix-and-match authorization -- as well as the authorization of Moderna and J&J boosters -- and then the CDC director will decide whether to sign off on ACIP's guidance