Pfizer says results from a trial of its COVID-19 vaccine booster shows the third shot is 95.6 percent effective against the virus. The drug giant and its partner, BioNTech SE, gave the booster to 5,000 people, an average of 11 months after they were fully vaccinated, in a randomized study. The study found those who received the vaccine and not the placebo were almost fully protected against symptoms. Crucially, the trial was carried out when the Delta variant—which has caused the recent surge in infections and deaths—was the predominant strain. The results could prompt regulators to expand the groups eligible for boosters.
