This month, the number of measles cases reported in California so far in 2025 jumped above the total for all of 2024.
There have been 16 measles cases reported in the Golden State so far this year, compared to 15 total last year and just four the year before. The highly contagious, sometimes-fatal disease was considered eradicated in the United States in 2000, but cases are returning amid declining vaccination rates and a large ongoing outbreak in Texas.
“The writing was on the wall that we were going to see more measles cases this year than we saw last year,” said Tara Greenhow, a pediatric infectious disease specialist with Kaiser Permanente in San Francisco.
“For infectious disease providers, this wasn’t a big surprise, because we saw rates overall of all immunizations decreasing during the pandemic,” Greenhow said. “The question was really not so much ‘if,’ it was really just ‘when.’”
Cases have been identified in Fresno, Los Angeles, Orange, Placer, Riverside, Sacramento, San Mateo, Santa Clara, Tuolumne and Yolo counties, and in Long Beach, which has its own health department.
The case in Santa Clara County was reported at the end of May, and was related to international travel. The person was never hospitalized, and while there was concern about exposures in the county, no other cases have been reported. It was the first case reported in the county since 2019.
In San Mateo County, a case was detected in February, but it was also related to international travel and did not lead to any known community transmission.
Across the country, health officials have reported 1,200 measles cases so far this year, including three deaths — the first in over a decade. Two children, both unvaccinated and without any known health complications, died in Texas. An adult in New Mexico also died. The person was also unvaccinated.
Children who are too young to get the measles, mumps, and rubella (MMR) vaccine, or those who have not been fully vaccinated, are highly likely to be infected if exposed to a contagious person. Measles is considered one of the most infectious diseases.
While California has a relatively high measles vaccination rate — 96.5% of kindergarteners as of 2022-3 — cases in the state are generally linked to travel to less-vaccinated areas.
When people travel to a place, like Texas, with an active outbreak, or to countries where the virus is still endemic, they can be exposed, but symptoms often don’t appear until they have returned home, meaning many more people may be exposed.
The outbreak in Texas has led to 750 cases around the state, including 97 people who were hospitalized. Nationwide about 12% of the reported cases have led to hospitalization.
Because of the virus’ highly contagious nature, health experts say a vaccination rate of 95% is needed to prevent outbreaks when exposures occur.
“In 2025, measles is making a troubling comeback,” wrote Dr. Erica Pan, the director of the California Department of Public Health, in a statement earlier this year. “This resurgence is a stark reminder that if we fail to follow the science and give into political posturing, progress in public health can be reversed.”
Health and Human Services Secretary Robert F. Kennedy Jr. has downplayed the importance of vaccines and questioned their safety, concerning public health experts.
The future of vaccine recommendations and schedules is uncertain. Kennedy recently replaced every member of the Advisory Committee on Immunization Practices, which makes recommendations to the CDC. The new members will meet for the first time June 25 in Atlanta.
Yvonne Maldonado, a professor of global health and infectious diseases at Stanford, is one of the 17 people removed from the committee.
“We are starting again to hear a lot of misinformation about these vaccines, and worse, about this disease that 30 years ago killed a million children a year,” Maldonado said.
“We need to get rid of this disease,” Maldonado said.
Despite her concerns, she is optimistic.
“The majority of people are still vaccinating their children. The majority of people are still listening to the science and the data and the lived experiences,” she said.
All the cases identified in California so far this year have been related to travel, either internationally or to Texas. There has yet to be evidence of community spread in California, according to the California Department of Public Health, but many public health experts are worried that with more unvaccinated people, the incredibly contagious virus is increasingly likely to find vulnerable humans to infect.