On Tuesday, the US Food and Drug Administration expanded its authorization of the Pfizer/BioNTech and Moderna Covid-19 vaccines. Now, adults ages 50 and older are able to get a second booster if at least four months have passed since their first one.

(SOURCE) https://www.cnn.com/2022/03/31/health/vaccine-covid-booster-omicron-wellness/index.html