Overview
- San Francisco’s health department, which confirmed an infant’s case Monday evening, announced Wednesday the city’s first measles infection in six years in an unvaccinated child who became contagious after international travel.
- Sacramento and Placer County officials said at a joint briefing Wednesday that the regional outbreak has reached 19 cases, with transmission concentrated among children and teens in homeschool enrichment settings.
- State data show 39 measles cases so far in 2026, with 85% in people under 20 and 95% unvaccinated or with unknown status, and health officials have reported two hospitalizations.
- California’s largest current cluster began with an unvaccinated toddler who traveled to South Carolina, in line with a broader U.S. resurgence the CDC counts at more than 2,200 cases and at least 48 outbreaks.
- Health leaders urge MMR vaccination, noting two doses are about 97% effective and that infants 6–11 months can get an early dose for international travel, while contact tracers work through the 21‑day incubation window.