SACRAMENTO, the United States, Feb. 12 (Xinhua) -- A measles outbreak was reported in California on Wednesday, with the largest cluster confirmed in Shasta County in the northern part of the state.
California is responding to its first measles outbreak in at least six years. Including the eight cases reported in Shasta, the California Department of Public Health (CDPH) has reported 17 confirmed measles cases statewide this year.
All eight individuals in Shasta were either unvaccinated or had unknown vaccination status, which has prompted state health officials to urge residents to verify their own status.
The outbreak came as the United States experienced its worst measles crisis in more than 30 years. The country reported 2,276 cases in 2025, the highest annual count since measles was declared eliminated in 2000, according to the U.S. Centers for Disease Control and Prevention.
Nationwide data from 2025 showed that 96 percent of measles cases occurred in unvaccinated people or those with unknown vaccination status, while only 3 percent occurred in individuals who had received at least one vaccine dose.
Measles is a viral disease that spreads through airborne droplets and can remain infectious in the air for up to two hours. Roughly 90 percent of unvaccinated people exposed to the virus will become infected, according to the CDPH.
The CDPH said two doses of the measles, mumps and rubella (MMR) vaccine provide about 97 percent protection. California reported more than 95 percent MMR vaccination coverage among kindergarteners for the 2024-2025 school year. ■