California's Interventions Improve Kindergartner Vaccination Rates

Earlier this year, the World Health Organization pointed to vaccine hesitancy as 1 of the top threats to global health in 2019.

This uncertainty surrounding childhood vaccinations is a growing concern in the United States as outbreaks of vaccine-preventable diseases, including measles and hepatitis A, have become increasingly more common. In the face of these preventable outbreaks, health officials in several states have started to question whether it is time to eliminate personal belief exemptions in order to ensure herd immunity and cut down on incidences of avoidable diseases.

The buzz around limiting exemptions to vaccination poses the question: does eliminating personal belief exemptions actually increase vaccination rates and cut the number of outbreaks and disease clusters that affect children?

That’s exactly what a study team led by investigators from the Department of Epidemiology at Emory University set out to evaluate in an observational study recently published in JAMA.

Prior to 2014, parents in the Golden State could claim a personal belief exemption by submitting a form declaring their objection. Since then, the state of California has implemented 3 interventions with the intention of increasing the uptake of vaccines among school-aged children.

The first intervention, Assembly bill 2109, was passed in 2014 and required parents to provide proof that they had discussed the risks of not vaccinating their child with a health care provider prior to obtaining a personal belief exemption.

The following year the state health and local health departments collaborated on a campaign to provide education to school staff on the “proper application of the conditional admission criteria, which allow students additional time to catch up on vaccination.”

And finally, Senate bill 277 was passed in 2016 eliminating personal belief exemptions entirely in the state of California.

In order to evaluate the outcomes of these 3 interventions, the investigators analyzed cross-sectional school entry data from 2000-2017. The primary outcome of the research was the annual rate of kindergartners who were not up-to-date on their vaccinations. The investigators also looked at the number of geographic clusters of schools with rates for kindergartners without up-to-date vaccination status that were higher than the rates for schools located outside of the cluster and the number of schools located inside the clusters.

The team found that during the 17-year study period, 9,323,315 children began attending kindergarten in the state of California, 721,593 of whom were not up-to-date on required vaccinations.

Prior to the 3 interventions, the statewide rate of kindergartners without up-to-date status for required vaccinations increased from 7.80% in 2000 to 9.84% in 2013. Following the implementation of the interventions, the rate decreased to 4.87% in 2017.

Furthermore, the interventions were also associated with a reduction in the risk of contact among kindergartners. The percentage chance for within-school contact among kindergartners without up-to-date vaccination status decreased from 26.02% in 2014 to 4.56% (95% CI, 4.21%-4.99%) in 2017.

Finally, the interventions were found to be linked with reductions in the number of schools that were included in the clusters of high rates of kindergartners without up-to-date vaccination status. During 2012-2013, there were 124 clusters that contained 3026 schools with high rates of kindergartners without up-to-date vaccination status. During 2014-2015, this decreased to 93 clusters containing 2290 schools, and during 2016-2017, there were 110 clusters that contained 1613 schools (95% CI, 1565-1691).

“In California, statewide legislation and educational interventions were associated with a decrease in the yearly rates of kindergartners without up-to-date vaccination status,” the authors of the report wrote in their conclusion. “These interventions were also associated with reductions in the number of schools inside the clusters with high rates of kindergartners without up-to-date vaccination status and the potential for contact among these kindergartners.”