California sees the most measles cases in 7 years amid a U.S. surge

Key Points:

• California has reported at least 40 confirmed measles cases in 2026, the highest annual total since 2019, amid a national resurgence of the highly contagious disease linked to declining vaccination rates.
• The majority of cases in California (95%) involve unvaccinated or immunization-unknown individuals, primarily children and young adults under age 20, highlighting vulnerabilities in community immunity.
• Three outbreaks have fueled the spread in California this year, including a significant one in Sacramento and Placer counties linked to travel-related exposure, with ongoing transmission expected to continue for several weeks.
• Nationwide, measles cases are nearing 2025's total of 2,287, the highest since 1991, with vaccination rates among kindergartners declining below the 95% herd immunity threshold in many states.
• Health officials emphasize the importance of timely MMR vaccination, especially for children and international travelers, and urge anyone suspecting measles infection to seek medical evaluation while taking precautions to prevent further spread.