Santa Clara County began administering the new COVID-19 booster vaccines Wednesday, offering protection against two subvariants of the omicron variant as well as the virus' original strain.

Federal regulators approved the boosters manufactured by Pfizer-BioNTech and Moderna last week. Both vaccines are bivalent, targeting the BA.4 and BA.5 subvariants of omicron as well as the original COVID strain.

The Moderna booster is available to adults while the Pfizer booster is available to people ages 12 and up.

The new boosters will be used for all future booster vaccinations for people ages 12 and up while the original mRNA vaccines are authorized for initial vaccine series for those aged 6 months to 4 years and also as a booster for kids between ages 5 and 11.

"The county of Santa Clara is committed to quickly making the bivalent vaccines readily available to our community," Santa Clara Valley Medical Center Associate Chief Medical Officer Dr. Jennifer Tong said in a statement. "Our hope is this will slow transmission and mitigate harm that may come from a fall or winter surge."

People are eligible for one dose of the omicron-specific boosters if it has been at least two months since completing their initial vaccination series.

Boosters will also be available via large health care providers as well as retail pharmacies like CVS.

People can make a vaccination appointment at a county-run clinic at covid19.sccgov.org/covid-19-vaccine-information.