The Food and Drug Administration has authorized a second booster dose of the COVID-19 vaccines made by Moderna and Pfizer for people over the age of 50.

The FDA also authorized a second Pfizer booster shot for people 12 and older who have compromised immune systems, while a second Moderna booster was authorized for adults over the age of 18 who have a compromised immune system.

The second booster shot can be administered four months after the first booster shot.

The agency made the decision without consulting its Vaccines and Related Biological Products Advisory Committee. The committee will meet on April 6 to discuss booster shots but is not expected to vote on recommending a fourth shot of either vaccine.

The CDC is expected to quickly sign off on the recommendation and will lay out the guidelines for who should get a second booster shot.