Vaccination rates in California schools decline; some students are prone to measles

Despite some of the strictest school vaccination laws in the United States, California reports that its share of vaccines in kindergarten students fell last year, who were immune to measles, including in 16 counties where students no longer have the immunity of feeders to one of the most infectious diseases.

New data from the California Department of Public Health suggests that 96.2% of California students in transition kindergartens and kindergartens received measles, mumps, and rubella in the 2023-24 school year, down from 96.5% of the previous year. and 93.7% of kindergarten students have the latest status of all immunizations, down from 94.1% in the same period last year. Data on vaccination rates for first-year students that are not available.

The childhood vaccination rate in California is still higher than in the United States overall. But public health experts say the decline in immunity rates poses two major risks: In a fatal outbreak that began in Texas, measles may be spread here, and immunity rates may continue to decline.

Experts say the trust of public health agencies in the 199 pandemic has worsened, and there is growing concern that deep politics and widespread disinformation online will only make it more difficult to reverse the downward trend.

A 95% vaccination rate, sometimes called “herd immunity,” is often considered the gold standard for preventing disease. This threshold not only prevents infection from gradually passing through a community, but also protects those who are unable to get vaccinated due to pregnancy, low immune function, or other serious health problems.

“Measles is so infectious,” said Dr. Chad Vicio, president of general pediatrics at Loma Linda University in San Bernardino County, where about 93.5% of kindergarten students were immune to measles last year.

When he was vaccinated with the disease, he said: “People who are not vaccinated are more likely to get infected.”

Measles is often associated with high fever and rash, but more severe cases can lead to pneumonia or encephalitis. Vercio said the disease is infected about 1-3 people per 1,000 people and one in five deaths.

After the 2014-15 measles outbreak at Disneyland, vaccine laws in California were tightened, making it difficult for parents to send their children to situations without a range of standard childhood vaccines, including lenses from DTAP, short shots from diphtheria, tetanus and tertussis; and MMR, abbreviated measles, mumps and rubella.

Still, childhood immunity rates in the state have been declining for most of the decade.

Vicio said he and other local pediatricians have seen “significant” in vaccine hesitation since the pandemic, including parents who refuse to discuss immunization with their doctors after they encounter misinformation about the vaccine online, including the debunk between vaccines and autism.

Last year, nearly two-thirds of California counties reported immunization rates below 95% of all childhood diseases, with 14 counties below 90%. Measles has a higher immunization rate, but 16 counties (or more than a quarter) still report less than 95% of counties.

The lowest immunization rate is Northern California. In Glenn and El Dorado counties, less than 80% of kindergarten and transition kindergarten students are fully vaccinated, while less than 81% of students with measles are. The lowest total vaccination rate in Sartre County reported was 73% and the lowest vaccination rate for measles was 75.8%.

Southern California usually performs better. Data shows that among the nearly 130,000 kindergarten students in Los Angeles County, more than 97% of MMR shots last year. Orange County reported an immunization rate of 97.4% for nearly 44,000 kindergarten students.

But San Diego County is the second-largest student in kindergarten students after La County, with immunization rates slightly below the 95% herd immunity benchmark, reaching 94.8%.

Data show that in Kern County, measles immunity rates among more than 19,000 kindergarten students are slightly higher than 91%, down from 1 percentage point the previous year. About 87.4% of kindergarten students received all the required photos.

“Distrust of health care providers and systems, and the spread of vaccine misinformation,” Kern County Public Health spokesman Michelle Corson said in a statement.

She said some residents face other obstacles in access to health care, including lack of insurance or transportation challenges. Coson said the county has already had a back-to-school vaccination drive and has a mobile health clinic that travels to more rural areas in the county to provide shooting.

State data shows that in Santa Cruz County, 91.8% of kindergarten students received measles last year, a rate that has dropped from 94.1% two years ago.

“We are very vulnerable,” said Dr. Lisa Hernandez, a public health official in the county. She said the scenic Santa Cruz is “baseline vulnerability” to infectious diseases such as measles, as relatively large people travel through the county to vacation and visit the University of California campus.

Many counties with relatively low vaccination rates have a higher share of students with independent learning or homeschool programs that do not involve classroom teaching or receive special education services in schools, even if they are not fully vaccinated.

Kern County says 9% of kindergarten students participate in such programs. In El Dorado County, nearly 20% of students are in Sutter County, which has the lowest vaccination rates in the entire county, whose share soars to nearly one quarter of kindergartens in the county.

Heather Orchard, an immunization expert and public health nurse in El Dorado County, said that despite the low vaccination rate in rural counties, the risk of measles outbreaks is less likely than large and more populous counties.

“I think our Dorado County has a low risk,” she said. However, she said the county is still working to make the vaccine available and share that information with families who send students to school.

California first tightened its childhood vaccination law after a measles outbreak at Disneyland, which spread among 131 people in California, highlighting the risk of a disease that was once thought to be eliminated. California reported five measles cases in 2025.

In 2015, state lawmakers approved Senate Bill 277, which eliminates parents’ ability to enumerate their personal or religious beliefs, which is why skipping the childhood vaccination required for schools. The law has caused the state's vaccination rate to increase by 5 percentage points, data shows.

Four years later, when accusing a few doctors of issuing fake medical exemptions for unvaccinated children, lawmakers passed SB 276, giving the state more power to review the exemptions. These collective efforts reduce exemptions from individual beliefs to zero, and medical exemptions to less than 1% statewide.

However, since then, vaccination rates for all children immunized and the rates of two-dose measles shootings have dropped.

Pediatrician who wrote two vaccines on two California vaccine laws, former state Senator Richard Pan (D-Sacramento) said his efforts to make schools safer for vulnerable children, even if immunization rates remain low in some areas.

“From a policy perspective, we’ve done everything we can,” Pan said. “And I think we’re doing a great job.”

But public health experts are preparing for childhood immunity rates so that they can continue to decline in the current political climate and as anti-vaccine movements become more mainstream.

“Now it's starting to be something like this red state, blue state,” said Richard Carpiano, a public policy professor at UC Riverside.

Carpiano and other experts say there is widespread concern that the Trump Administration’s decision to fund public health work and medical research will only worsen health disparities across the country. He noted that rather than vaccinating children in the recent measles outbreak, Robert F. Kennedy, Jr.

“We are going backwards. We are creating all these different types of vulnerabilities,” Carpiano said. “The lighter liquid just put in these little sparks about freedom, personal choice and parental rights.”