California reported a decline in the proportion of kindergarten students vaccinated against measles, including 16 counties that no longer have herd immunization for one of the most infectious diseases of all time, despite having some of the country’s strictest school vaccination laws.
New data from the California Department of Public Health shows that last year, 96.2% of transitional kindergarten and kindergarten students were vaccinated against measles, mumps and rubella from 2023-24, starting from 96.5% the previous year. Additionally, 93.7% of kindergarten students were up to date with all vaccinations, down from 94.1% in the same period last year. Data on higher first-year students’ vaccination rates were not available yet.
Vaccination rates in California are still higher than in the US as a whole. However, public health experts say lower vaccination rates create two major risks. This means that measles could spread here amid the fatal outbreak that began in Texas, and vaccination rates could continue to decline.
The Covid-19 pandemic has exacerbated confidence in public health agencies, experts say.
The 95% vaccination rate, sometimes referred to as “school immunity,” is generally considered the gold standard for disease prevention. This threshold not only prevents infections from tearing the community, but also protects those who are unable to get vaccinated due to pregnancy, immunodeficiency, or other serious health issues.
“Measles are very infectious,” said Dr. Chad Versio, director of the Department of Children’s Health at Loma Linda University in San Bernardino County.
With fewer people offset by the illness, “the chances of infection by people who have not been vaccinated are very high,” he said.
Measles is most often associated with high fever and rashes, but more serious cases can cause pneumonia or encephalitis. The disease kills about 1-3 people for every 1,000 people infected, leading to one hospitalization in five cases, Vercio said.
The California vaccine law, toned in the wake of the 2014-15 measles outbreak at Disneyland, makes it difficult for parents to send their children to school without a series of standard pediatric vaccines, including shots called DTAP. MMR, short for measles, mumps, and rubella.
Still, the state’s childhood vaccination rates have fallen for most of the decade.
Vercio said he and other local pediatricians have seen a “significant” rise in vaccine reluctance since the start of the pandemic, including parents who refuse to encounter immunity online after encountering misinformation online about vaccines that include links between vaccines and autism.
Last year, almost two-thirds of California counties reported vaccination rates for all childhood diseases, less than 95%, with 14 counties below 90%. Although measles vaccination rates were high, 16 counties (one in four) reported less than 95%.
The lowest vaccination rate was in Northern California. In Glen and Eldorado counties, under 80% of kindergartens and kindergarten students were fully vaccinated, with less than 81% against measles. Sutter County reported the lowest vaccination rate at 73% and 75.8% for measles.
Southern California is generally better. Of the approximately 130,000 kindergarten students in Los Angeles County, more than 97% have received more than two MMR shots last year, data show. Orange County reported a 97.4% vaccination rate for approximately 44,000 kindergarten students.
However, San Diego County, which has the second-largest kindergarten student after LA County, saw vaccination rates above 94.8% just below the 95% herd immunity benchmark.
In Kern County, measles vaccination rates among more than 19,000 kindergarten students were shy at 91%, down more than 1% from the previous year, data show. Approximately 87.4% of kindergarten students received all the shots they needed.
Michelle Colson, a spokesman for the Kern County Department of Public Health, said in a statement that “distrust of healthcare providers and systems and the spread of vaccine misinformation” is contributing to vaccine reluctance.
She said some residents also face other barriers to accessing healthcare, including lack of insurance and transportation challenges. Corson said the county runs a return to school vaccination drive and has a mobile health clinic that travels to more rural areas of the county and offers shots.
In Santa Cruz County, 91.8% of kindergarten students were vaccinated with measles last year. This has been down from 94.1% two years ago, state data shows.
“We are vulnerable,” said Dr. Lisa Hernandez, the county public health officer. The scenic Santa Cruz has “baseline vulnerabilities” to infectious diseases such as measles, she said.
Many counties with relatively low vaccination rates have a higher share of students enrolled in independent research or homeschool programs, even if they do not have classroom guidance or are unable to receive special educational services at schools.
Kern County said 9% of kindergarten students are enrolled in such programs. In El Dorado County, nearly 20% of students have skyrocketed to nearly one in four kindergarten students in the county, Tiny Sutter County, which has the lowest overall vaccination rate in the state.
Heather Orchard, an El Dorado County Public Health vaccination specialist and public health nurse, said despite lower vaccination rates in rural counties, the risk of measles outbreaks is lower than in larger population-dense counties.
“In Eldorado County, we feel our risk is low,” she said. But she said the county still has the vaccine available and shares the information with families who are sending it to schools.
California first tightened the childhood vaccination laws 10 years ago after the outbreak of measles at Disneyland, which spread to 131 people in California, highlighting the risk of once thought disease. California reported five measles cases in 2025.
In 2015, state lawmakers approved Senate Bill 277. This eliminated the parent’s ability to cite personal or religious beliefs as a reason to skip school-needed childhood vaccinations. The law led to a five percentage point increase in the state’s vaccination rate, data shows.
Four years later, amid a claim that a small number of doctors are issuing fake medical exemptions to unvaccinated children, legislators passed SB 276, giving the state more power to scrutinize those exemptions. These collective efforts have reduced the exemption to zero for personal beliefs and reduced the medical exemption to less than 1% statewide.
However, since then, vaccination rates for all childhood vaccinations and two-dose measles shots have declined, state data shows.
Sen. Richard Pan (D-Sacramento), a pediatrician who wrote both California’s vaccine laws, said his efforts made schools safer for vulnerable children, even if he admitted that vaccination rates remained low in certain areas.
“From a policy perspective, we did what we could,” Pan said. “And we feel we did well.”
However, public health experts are preparing for childhood vaccination rates in the current political climate and as the anti-vaccine movement becomes more mainstream.
“Now we’re starting to get to this kind of red state, the blue state,” said Richard Carpiano, a public policy professor at UC Riverside who studied the vaccine.
Carpiano and other experts said there is a general concern that the Trump administration’s decision to invest funding public health efforts and medical research would only exacerbate health disparities across the country. He said instead of encouraging families to vaccinate their children during this recent measles outbreak, Trump’s U.S. Department of Health and Human Services Secretary Robert F. Kennedy Jr. promoted vitamin A and cod liver oil as effective treatments.
“We’re backing down, and we’re creating all these different types of vulnerabilities,” Carpiano said. “Lighter liquids were thrown all over these little sparks about freedom and personal choice and parental rights.”
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