https://www.mercurynews.com/2022/03/29/fda-authorizes-second-booster-for-50-as-stealth-omicron-subvariant-dominates-u-s/

The FDA said Tuesday that people age 50 and older may get a second Pfizer or Moderna COVID-19 booster shot four months after their first as the highly contagious omicron subvariant BA.2 was reported to account for more than half of U.S. cases.

The Food and Drug Administration also said those who have had organ transplants or otherwise have compromised immunity may get a second booster by Pfizer if they are age 12 or older or by Moderna if they are age 18 or older.