Pfizer says it has promising data about a coronavirus vaccine booster.
The company says it will soon apply for emergency use authorization for a third shot.
Researchers say a booster shot six to 12 months after full vaccination is likely to provide the highest level of protection, especially against the highly contagious delta variant.
Studies show antibody levels are five times greater in people 18 to 55 who get a third shot. For those 65 to 85, antibody levels are 11 times higher.
Also pending approval, Pfizer says it wants to study an updated version of its vaccine.
The company’s lead researcher says it would target the delta variant, which currently represents 83% of COVID-19 cases in the U.S.