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Pfizer says booster shot shows 95.6% efficacy against COVID-19

Pfizer said there were only 5 cases of COVID-19 in the booster shot group during the trial, and 109 cases in the group of individuals who received a placebo.

NEW YORK — Pfizer announced Thursday morning that data from its Phase 3 trial found the booster dose of its COVID-19 vaccine was highly effective in protecting against the coronavirus, including the Delta variant. 

The company said its trial included more than 10,000 individuals and found the Pfizer-BioNTech booster showed a vaccine efficacy of 95.6% when compared to those who did not receive a booster. 

Pfizer said booster shots were administered approximately 11 months, on average, after trial participants received their second-dose of the vaccine. 

The trial was underway when Delta was the prevalent strain, according to the company's announcement. During the study, there were only 5 cases of COVID-19 in the booster group, and 109 cases in the group of individuals who received a placebo.

The company said the data is the first efficacy results from any randomized, controlled COVID-19 vaccine booster trial.

Last month, the Centers for Disease Control and Prevention approved the Pfizer booster shot for older Americans and others at high risk from the virus. 

On Wednesday, the Food and Drug Administration signed off on extending COVID-19 boosters to Americans who got the Moderna or Johnson & Johnson vaccine and recommended allowing "mixing and matching" of shots. A panel of experts is scheduled to meet Thursday before the CDC finalizes official recommendations for who should get the Moderna or J&J boosters and when. 

The latest moves from the FDA would expand by tens of millions the number of Americans eligible for boosters and formally allow “mixing and matching” of shots — making it simpler to get another dose, especially for people who had a side effect from one brand but still want the proven protection of vaccination.

The Associated Press contributed to this report.