Twelve Alameda County residents who attended a wedding in Wisconsin last week tested positive for COVID-19, and five of them have been diagnosed with the omicron variant, health authorities said Friday.
The Alameda County Department of Public Health said genomic sequencing data that identifies the variant is not yet available for all 12 cases.
One of the individuals attended the Nov. 27 wedding after returning from international travel.
All 12 individuals were fully vaccinated, and most had received boosters, the department said. Their symptoms are mild and no one has been hospitalized. All 12 are between the ages of 18 and 49
Close contacts are being notified.
Much remains unknown about omicron, including whether it is more contagious, as some health authorities suspect, whether it can thwart vaccines and whether it makes people as sick as the original strain.
New COVID-19 cases in South Africa, which first alerted the world to omicron last week, have burgeoned from about 200 a day in mid-November to more than 16,000 on Friday.
The omicron variant was first identified in a U.S. resident in San Francisco on Dec. 1 and has since been detected in a handful of other states so far, including New York, Colorado and Hawaii.
Some of the U.S. cases involve people who hadn’t traveled recently, meaning the variant was likely already circulating domestically in some parts of the country.
Experts say the best protection against the variant is vaccination.
The Associated Press contributed to this story.
