Pfizer study: Booster shot restores vaccine efficacy to 95.6%


FILE – In this Jan. 21, 2021, file photo, a medical staff member prepares the Pfizer COVID-19 vaccine at Tudor Ranch in Mecca, Calif. (AP Photo/Jae C. Hong, File)

NEW HAVEN, Conn. (WTNH) — 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 vaccine efficacy of 95.6% 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 result 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 said anyone eligible for an extra dose can get a brand different from the one they received initially.

The Associated Press contributed to this report.

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