2 measles cases test whether the Bay Area can keep the virus from spreading

The Bay Area has now recorded two measles cases in the first weeks of 2026 — an early test of whether one of the nation’s most highly vaccinated regions can keep the virus from gaining ground as the United States approaches the loss of its measles-free status.

The latest infection, reported in an unvaccinated person in San Mateo County, has not led to additional cases. Health experts say that’s largely because vaccination rates across much of the Bay Area remain high enough to give the...