News Federal agencies authorize second COVID-19 booster shot for Americans 50 and older March 29, 2022Karen Weintraub, USA TODAYComments Off on Federal agencies authorize second COVID-19 booster shot for Americans 50 and older A second booster shot of the Pfizer or Moderna COVID-19 vaccine is allowed for those 50 and up. Immunocompromised can now get a fifth shot.