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California's Aggressive Pro-Vaccination Policies Have Made a Big Difference

A new study finds that the percentage of kindergartners in the state without up-to-date vaccinations dropped from nearly 10 percent in 2013 to under 5 percent in 2017.
Vials of measles, mumps, and rubella vaccines are displayed at a Walgreens Pharmacy in Mill Valley, California, on January 26th, 2015.

Vials of measles, mumps, and rubella vaccines are displayed at a Walgreens Pharmacy in Mill Valley, California, on January 26th, 2015.

Federal health officials recently announced that there have been 971 cases of measles in the United States so far this year—a higher number than the 963 cases reported for all of 1992, the year America saw its last major outbreak. California has been ahead of the curve in dealing with this public-health problem, and just-published research finds that the state's efforts have paid off in a big way.

The Journal of the American Medical Association reports that two new state laws limiting exemptions from mandated vaccines, along with an educational campaign aimed at school staff members, have greatly reduced schoolchildren's risk of contracting the disease.

Between 2013 and 2017, California saw "a decrease in the yearly rates of kindergartners without up-to-date vaccination status," reports a research team led by S. Cassandra Pingali of Emory University. An accompanying editorial calls this "a promising outcome in California, resulting from policy changes."

The state's government has been dealing with the issue of vaccination exemptions for most of this decade. In 2012, then-Governor Jerry Brown signed into law a bill that tightened requirements for obtaining personal-belief exemptions, which allowed parents to keep their children unvaccinated. The 2012 bill mandated that parents discuss their options with a health-care practitioner before receiving an exemption.

A more forceful bill that eliminated personal-belief exemptions—allowing them only if a physician stated it was in the child's medical interest—was signed into law in 2015. Also that year, the state "provided educational materials to school staff on the proper application of conditional admission for kindergartners who were not up to date on required vaccinations," the study states.

In recent weeks, the legislature has been working on still-more stringent rules in response to reports that some physicians are providing exemption certifications without good reason. But even as that debate continues, this new research shows the earlier efforts have already been quite effective.

Specifically, the statewide rate of kindergartners who were not up to date on their required vaccinations dropped from 9.84 percent in 2013 to 4.87 percent in 2017.

As a result, the odds that two children lacking proper vaccinations would come into contact—a huge risk factor for spreading measles—fell from 26 percent in 2014 to 4.5 percent in 2017.

The report notes there are still geographical clusters where the vaccination rate is below average. But these have shrunk considerably from 2012 to 2017, and are now mostly located in California's rural far north.

What's more, even within those clusters, the number of schools with high rates of kindergartners lacking up-to-date vaccination status decreased from 2,290 in the 2014–15 school year to 1,613 in 2016–17.

In an editorial accompanying the study, Matthew Davis and Seema Shah of Northwestern University applaud these results in California, but argue that "because of the ease of domestic and international travel," individual states can only do so much on their own.

"The best way to remedy the current system failure regarding measles vaccination may be to adopt a unified national approach to prohibit non-medical exemptions," they conclude, "and thereby regain the degree of nationwide protection against vaccine-preventable disease from which children and other community members will benefit."