SAN FRANCISCO (CBS SF) – UCSF Medical Center announced Wednesday that they have vaccinated nearly 10,000 frontline staff from COVID-19 and have begun distributing second doses.

Hospital officials said in a statement that the vaccinations so far are only a part of the 21,500 employees in the initial phase of distribution.

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Frontline employees receiving the Pfizer shots include custodial workers, nurses, phlebotomists and respiratory therapists, along with physicians that are at higher risk of being exposed to COVID-19 at work.

UCSF Health said they expect to administer about 1,600 doses daily if supplies remain stable.

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The medical center received its first shots from Pfizer on December 16 and have since received additional of vaccines from Pfizer and Moderna. Officials previously said that the vaccine would eventually be distributed to higher-risk patients, such as those 65 and older and those with chronic medical conditions, along with everyone in the university community.

UCSF’s announcement comes a day after San Francisco Public Health Director Dr. Grant Colfax said SFDPH has vaccinated more than 6,000 people, including frontline staff at Zuckerberg San Francisco General Hospital and residents at Laguna Honda Hospital.

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“This is an unprecedented undertaking, the mass vaccination of the entire nation to end the pandemic. We are working hard, but right now vaccine supply remains limited, and many questions remain unanswered,” Colfax said at Tuesday’s COVID-19 briefing. “We expect that everyone who wants a vaccine will get one eventually and we will work together as we have done throughout this pandemic to make this happen.”