https://www.mercurynews.com/2021/12/08/covid-east-bay-omicron-cases-were-vaccinated-kaiser-staff/

Kaiser Permanente said Wednesday that 11 of its vaccinated and boosted Oakland Medical Center workers were among a cluster of East Bay COVID-19 cases linked to the omicron variant that has alarmed health officials worldwide, and that at least 16 patients and other staff were exposed to them.

The revelation comes five days after Alameda County health officials said they were investigating 12 local COVID-19 cases linked to a Nov. 27 wedding in Wisconsin, which one of the infected people had attended upon return from international travel, and that at least five were confirmed to have the omicron variant.