L.A. County-USC Medical Center was among the hospitals where the Pfizer vaccine was being administered.
The rollout comes as hospitals across the state have been struggling to care for patients amid diminished ICU capacity, which fell to 0% in the 11-county Southern California region earlier this week.
Staff at Glendale Memorial Hospital began receiving the vaccine shot on Thursday, while nearly 600 L.A. County health care workers were also vaccinated.
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"I did receive the vaccination this morning, I do feel great," Dr. Tamara Chambers, chief medical director at L.A. County-USC Medical Center, said during an online briefing.
"I'm so grateful that I'll be able to continue to provide safe and effective care to patients - particularly in the critical-care and the ICUs during their most dire times of need," Chambers said, "and that soon we'll be able to move it out to the communities so that we can get rid of this pandemic forever."
The Pfizer vaccine requires two shots, given weeks apart, meaning that the entirety of its protection will not be widespread for some time.
Meanwhile, the U.S. stood on the verge of adding a second COVID-19 vaccine to its arsenal Friday as the outbreak descended deeper into its most lethal phase yet, with the nation regularly recording over 3,000 deaths per day.
The Food and Drug Administration was evaluating a shot developed by Moderna Inc. and the National Institutes of Health and was expected to give it the green light soon, clearing the way for its use to begin as early as Monday.
The Associated Press contributed to this report.