People in the age group can get the additional shot at least four months after their first booster. Those 12 and older with certain immune deficiencies are also eligible.
Federal officials appear to be coalescing around a plan to offer people 65 and older — and possibly some younger adults — the option of another booster, in case infections surge again soon.
A drug to prevent preterm birth may provide the next test of the agency’s process for speedily getting drugs on the market, despite limited evidence that some work.
The company said the vaccine produced a strong immune response in children younger than 6, but proved only about 40 percent effective in preventing symptomatic Covid-19.