An independent panel of experts advising the Food and Drug Administration voted on Thursday to recommend a booster shot for many recipients of the Moderna coronavirus vaccine, and on Friday to recommend authorizing booster shots of Johnson & Johnson’s one-dose coronavirus vaccine for people 18 years or older, at least two months after the first dose.

So what happens now? There are further steps at the F.D.A., then steps at the Centers for Disease Control and Prevention, and the process ends with the states. Here’s how it breaks down.

  • The F.D.A., a federal agency of the Department of Health and Human Services that controls and supervises medications and other elements related to public health, takes up the advisory panel’s recommendation, which includes the question of who should be eligible. The advisory panel’s votes are not binding, but the F.D.A. typically follows them.

  • The F.D.A.’s top official — its acting commissioner, Dr. Janet Woodcock — issues the agency’s final determination on whether to authorize the boosters and for whom. Such decisions are typically issued within a few days of advisory committee meetings.