A Reserve Citizen Airman assigned to the 307th Medical Squadron prepares a syringe before administering a COVID-19 vaccination at Barksdale Air Force Base, Louisiana, Nov. 7, 2022. The unit was administering the shots as part of on-going mitigation efforts. (U.S. Air Force/Senior Airman Celeste Zuniga via Bay City News)

Appointments for Santa Clara County children under age 5 to receive the bivalent COVID-19 booster vaccine are now open at county-run vaccination clinics, public health officials said Wednesday.

Federal regulators expanded eligibility last week for the omicron-specific booster. The updated booster has been available to everyone age 12 and up since early September and to children between the ages of 5 and 11 since mid-October.

The bivalent boosters target both the initial COVID-19 strain and the BA.4 and BA.5 subvariants of the highly contagious omicron variant. Since their approval by federal regulators, they are now used for all booster vaccinations in any age group.

Children between the ages of 6 months and 5 years who received the initial Moderna COVID-19 vaccine are eligible for the Moderna booster if they completed their initial vaccine series at least two months ago.

For children aged 4 and younger who have not yet started their three-dose primary series of the vaccine manufactured by Pfizer-BioNTech, the updated booster will be used as the third dose following two doses of the original Pfizer vaccine, according to the FDA.

Children who have already received all three vaccine doses in the Pfizer series are not eligible for a booster dose at this time, FDA officials said, but the agency plans to review safety and effectiveness data in January for giving those children a fourth dose with the updated booster.

“We recommend that children get vaccinated for both COVID and flu, and that their families do the same,” county Health Officer Dr. Sara Cody said. “This will help keep people safe and healthy over the winter holiday season.”

Only about 18 percent of eligible Santa Clara County children under age 5 have completed their primary vaccination series, according to county data.

While the available COVID vaccines don’t completely eliminate a person’s ability to contract the virus, it does highly reduce the chance of becoming seriously ill with COVID or dying because of it.

“Vaccination will not only keep your family safe, but it will reduce the strain on our local hospitals and healthcare providers, so we ask all County residents to do everything they can to keep our community safe,” said Dr. Jennifer Tong, Santa Clara Valley Medical Center’s associate chief medical officer.

COVID vaccines are available at primary health care providers, retail pharmacies and via the county’s health care system.

Vaccination appointments and information about the location of vaccine clinics can be found at https://covid19.sccgov.org/covid-19-vaccine-information.