Pfizer says it is about to seek U.S. authorization for a third dose of its COVID-19 vaccine.
The company said Thursday that another shot could dramatically boost immunity and maybe help ward off the latest worrisome coronavirus mutant.
Research from multiple countries shows the widely used COVID-19 vaccines offer strong protection against the highly contagious delta variant.
But virus-fighting antibodies naturally wane. Pfizer says early data from a company trial suggests people's antibody levels jump after they get a third dose. But the filing doesn't mean third doses would be rolled out any time soon.
Public health officials would have to decide if they're really needed.