Riverside County residents were allowed Thursday to sign up to receive one of 3,900 COVID-19 vaccine doses to be administered at a series of county-run clinics, and all appointments were quickly taken.

The reservation window opened at noon, and according to the Riverside University Health System, all of the available slots were filled by early afternoon, prompting officials to begin planning additional clinics in the coming days. Dates and locations will be announced by RUHS, possibly Thursday or Friday.

Riverside County received a total of 26,000 doses of Pfizer vaccine this week. The bulk of the batch is headed to private entities countywide.

“This is important news to so many of our residents who are eager to be vaccinated,” Supervisor Karen Spiegel said Wednesday. “We also ask for your patience. We continue to have very limited vaccine quantities and a high demand within the community for it. The county is distributing vaccine as quickly as we receive it.”

Gov. Gavin Newsom announced last week that residents 65 and older are now eligible to receive the vaccine, following new guidance from the federal government. The previous age requirement for tier 1 of Phase IB was 75 years old.

Several free vaccine clinics are scheduled countywide, as officials continue to work to speed up the rate of immunizations.

Appointments are mandatory, and demand is so high that available time slots that went online last week were filled within two hours, officials said.

Appointments can be made via www.ruhealth.org/covid-19-vaccine.

The scheduled clinics will continue to accommodate residents in Phase IA of the state’s vaccine distribution plan, including health care workers and residents of long-term care facilities.

Residents in tier 1 of Phase IB will also be allowed to get vaccinated — people aged 65 and over and select essential workers, such as those in education, child care, emergency services and food and agriculture.

Inoculation is free, but people will be asked to provide medical insurance information, although insurance is not required. People planning to get vaccinated must register in advance and bring the required paperwork to prove their eligibility.

Vaccination clinics, which are already fully booked, are scheduled from 8:30 a.m. to 4 p.m. Friday and Saturday at Diamond Stadium in Lake Elsinore, 500 Diamond Drive; Saturday and Sunday, between 8:30 a.m. and 4 p.m., at Fullenwider Auditorium at the Indio Fairgrounds, 46350 Arabia St.; and Sunday and Monday from 8:30 a.m. to 4 p.m. at the Perris Fairgrounds, 18700 Lake Perris Drive.

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