For people who received the AstraZeneca vaccine, a Pfizer booster can be used in people ages 12 years and older and a Moderna booster can be used in people ages 18 years and older at least 5 months after completion of the AstraZeneca primary vaccination.

Moderately or severely immunocompromised recipients should receive a single mRNA COVID-19 vaccine dose (Pfizer or Moderna) at least 28 days after their completion of the AstraZeneca primary vaccination. They should receive an mRNA booster dose at least 3 months after the mRNA dose.

For more information, see the CDC recommendations for people who received COVID-19 vaccines outside of the United States.