Bay Area public health officials confirmed this week that an unvaccinated adult in San Mateo County has tested positive for measles, marking what appears to be California’s first confirmed case of the disease in 2026.
The person had recently traveled outside the United States, a common source of measles infections in the U.S., according to Preston Merchant, a spokesperson for the county’s health department.
“We are still working on reaching anyone who may have been exposed, but so far no one else has developed symptoms,” Merchant said…