California has experienced a concerning decline in measles vaccination rates among kindergarten students, with 16 counties falling below the critical threshold needed for community protection, according to new state health department data.
The percentage of transitional kindergarten and kindergarten students vaccinated against measles, mumps, and rubella dropped to 96.2% in the 2023-24 school year, down from 96.5% the previous year. The overall rate for all required immunizations also decreased to 93.7% from 94.1%.
While California maintains higher childhood vaccination rates than the national average, public health experts warn this downward trend could leave communities vulnerable to measles outbreaks, especially given the recent cases in Texas. A vaccination rate of 95% is considered necessary to prevent disease spread and protect those who cannot receive vaccines due to medical conditions.
Northern California reported the lowest immunization rates. Glenn and El Dorado counties recorded less than 80% of kindergarten students fully vaccinated. Sutter County had the state's lowest rate at 73% for all vaccines and 75.8% for measles specifically.
Southern California fared better, with Los Angeles County reporting over 97% of its nearly 130,000 kindergarten students received the required measles shots. However, San Diego County's rate fell just below the 95% benchmark to 94.8%.
Health officials attribute the decline to several factors, including increased vaccine hesitancy following the COVID-19 pandemic and the spread of medical misinformation online. Some counties also face healthcare access barriers, such as lack of insurance and transportation challenges.
Despite having some of the nation's strictest school vaccination requirements, California has seen declining immunization rates for nearly a decade. The state previously strengthened its laws after a 2014-15 Disneyland measles outbreak, eliminating personal belief and religious exemptions for required school vaccines.
Public health experts express growing concern that political polarization and widespread online misinformation may make it increasingly difficult to reverse this downward trend in vaccination rates, potentially putting more communities at risk for preventable disease outbreaks.