On March 29, 2022, the CDC began recommending an additional booster dose for certain individuals. Specifically, those who are severely immunocompromised or 50+ years old may now get another dose of Pfizer or Moderna four months after their prior dose. Additionally, people who have only had the J&J first dose and J&J booster can now get a Pfizer or Moderna booster. However, the CDC has not yet updated its definition of up to date to require these boosters.