https://www.mercurynews.com/2021/12/10/covid-santa-clara-county-reports-first-omicron-case/

Santa Clara County confirmed its first COVID-19 case of the worrisome omicron variant Friday whose rapid spread in other countries has alarmed health officials worldwide.

County health officials said the infected person is a county resident who was fully vaccinated but had not received a booster shot and had recently returned from domestic travel out of state. The person, whose age and gender they did provide, is “in isolation.”