In a sweeping action responding to debate and speculation over the last week, the Food and Drug Administration (FDA) approved COVID-19 boosters from Moderna and Johnson & Johnson Wednesday. The FDA also approved the use of a vaccine brand different from the one Americans received from their first dose(s).

“Today’s actions demonstrate our commitment to public health in proactively fighting against the COVID-19 pandemic,” acting FDA Commissioner Janet Woodcock said in a press release. “The available data suggest waning immunity in some populations who are fully vaccinated. The availability of these authorized boosters is important for continued protection against COVID-19 disease.”

Here’s what the amended emergency use authorizations now cover, according to the release:

• The use of a single booster dose of the Moderna vaccine at least 6 months after initial vaccination for people:
  • 65 years of age and older
  • 18 through 64 years of age at high risk of severe COVID-19
  • 18 through 64 years of age with frequent risk of institutional or occupational exposure
• The use of a single booster dose of the J&J vaccine at least 2 months after initial vaccination for all adults
• The use of each of the available vaccine booster dose in eligible individuals, regardless of what vaccine they initially got

“We will work to accrue additional data as quickly as possible to further assess the benefits and risks of the use of booster doses in additional populations and plan to update the healthcare community and public with our determination in the coming weeks,” FDA Center for Biologics Evaluation and Research Director Peter Marks said.

Last week, an advisory panel to the FDA unanimously approved both the Moderna and J&J boosters. Reports of the FDA’s approval of mix-and-match boosters came out earlier this week.

The FDA isn’t the only regulating body to rule on boosters. An influential panel convened by the Centers for Disease Control and Prevention is expected to meet Thursday to offer more specifics on who should get boosters and when. Their recommendations are subject to approval by the CDC director.