During a news conference on Wednesday led by Gov. Gavin Newsom, California Health Secretary Dr. Mark Ghaly encouraged residents to "absolutely" sign up to get a booster shot.
The current rules state people who initially received Pfizer or Moderna vaccinations are eligible for a booster six months later if they're 65 or older, or are at high risk of COVID-19 because of health problems or their job or living conditions. Because the single-dose Johnson & Johnson vaccine hasn't proven as effective as its two-dose competitors, any J&J recipient can get a booster at least two months later.
"The CDC was very clear that they had two categories: groups that should get the booster and groups that may," said Ghaly. "If you think you will benefit from getting a booster shot, I encourage you to go out and get it. Supply is available."
According to the CDC, those who should get a booster include adults 65 years and older, adults in long-term care settings and people with underlying medical conditions between the ages of 50 and 64.
Those who are allowed should they choose include people who work or live in high-risk settings such as health care facilities, schools, homeless shelters or correctional facilities.
This week, Pfizer asked officials to allow boosters of its COVID vaccine for anyone 18 or older. Anyone eligible for a booster doesn't have to stick with their initial vaccination type and can get a different company's vaccine, what's called mixing and matching.
According to Newsom, almost 90% of eligible adults in California have received at least one dose of the COVID vaccine.
The Associated Press contributed to this report.