LOS ANGELES (AP) — Los Angeles County has begun making booster doses of the Pfizer COVID-19 vaccine available to eligible population groups.

The move Friday follows Centers for Disease Control and Prevention endorsement of a third shot for those who got their second shot at least six months ago.

Boosters are available at hundreds of sites offering the Pfizer vaccine. Residents seeking the booster shot must bring proof they received two previous Pfizer doses.

Eligibility includes people age 65 or older, residents of long-term care facilities, people 18 to 64 with underlying medical conditions and those 18 to 64 years with high occupational risk.