The U.S. Food and Drug Administration has expanded eligibility for booster doses of Pfizer’s COVID-19 vaccine to include adolescents ages 12 to 15. The agency also announced that all people can now get a booster dose five months after they were fully vaccinated rather than the six month interval that was originally authorized.

Additionally, the FDA authorized a third dose of Pfizer’s vaccine for children ages 5 to 11 with certain conditions that compromise their immune systems, including those who have undergone solid organ transplants.

The FDA has determined that these steps are necessary to help combat the spread of the Omicron variant, which has driven a surge in cases that has already surpassed last year’s winter peak.