The Centers for Disease Control and Prevention vaccine advisory committee issued recommendations Wednesday for using Pfizer's two-dose vaccine in children as young as 12.
It's the only vaccine authorized for teens and kids ages 12 to 17.
Some locations in the Golden State started administering doses Wednesday night, just hours after the announcement.
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Some kids in Southern California rushed to get in line to get vaccinated.
"I am so excited, I've been waiting for this moment for so long. I just want to go back to normal and I just want this to end already," said teen Olivia Diamond "I'm so ready to be able to be with my friends and go to school."
CVS Pharmacy is offering appointments through its online scheduler, although an appointment is not required.
"I think it's really awesome because I'm going to be able to see my aunt and my friends," said Reese Charfen of Redondo Beach.
Gov. Gavin Newsom said expanding the vaccine to teens is the next step in reopening the state next month.
The move comes as the state encourages schools to resume in-person teaching and remains on track to lift many virus-related restrictions by mid-June.
The state has the nation's lowest positivity rate at 1%, while 61% of those eligible have had at least one shot, said Dr. Mark Ghaly, the state's health secretary. More than 30% of youths ages 16 and 17 have at least one vaccination.
Experts say children must be vaccinated if the nation is to reach the 70% to 85% of the population needed to reach what is known as herd immunity.
California will not now require the coronavirus shots for students as it does other vaccines, Ghaly said, given the emergency use authorization. Minors also need consent from their parents or guardians in most cases.
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But the state is working with local officials and community groups to encourage their use through things like targeted social media and "micro-influencers," the officials said.
That varies by location and does not necessarily include celebrities, but "trusted voices" like pediatricians and other healthcare workers, religious and school leaders.
The Associated Press contributed to this report.