SANTA CLARA COUNTY, Calif. (KRON) — A Santa Clara County resident has been reported to be the first in the county to test positive for the COVID-19 omicron variant, county officials said in a press release.

The individual in isolation is fully vaccinated but did not receive a booster shot.

The individual had recently returned from domestic travel out of the state, according to the release.

“Although there are still many unknowns about this variant, we strongly recommend getting vaccinated and getting your booster if you haven’t already to help guard against Omicron,” Dr. Sara Cody, Health Officer and Director of Public Health, County of Santa Clara said in the release. “It is a new variant, but we know what to do, and that’s to continue with all our layers of protection: Vaccinate, boost, mask, ventilate, distance, and test often.”

The mild case of omicron was caught by health officials after the adult felt symptoms the last day of November.

Dr. Sara Cody says the adult had planned on getting their booster shot this month. Her advice to others to help prevent the spread of omicron: vaccinate, boost, mask, test, ventilate and distance.

Residents are doing well with vaccinations in Santa Clara — Around 80% but COVID testing officer Dr. Martin Fenstersheib says only 39% of those eligible to get a booster have done so.

Infection disease expert at UCSF, Dr. Peter Chin-Hong says nation vaccination numbers are improving since the first known U.S. case of omicron was discovered in San Francisco on Dec. 1.

Dr. Chin-Hong says the mild symptoms of Santa Clara County’s first case of the new variant confirm what experts have been saying for months: Vaccines work.

Santa Clara County began accepting appointments for those ages 16 and older to receive a Pfizer booster shot.