HealthDay News — Implementation of a policy that eliminated nonmedical exemptions from school entry requirements correlated with an increase in vaccination coverage and a reduction in nonmedical exemptions in California, according to a study published online Dec. 23 in PLOS Medicine.
Sindiso Nyathi, from the Stanford University School of Medicine in California, and colleagues estimated the correlation between California’s 2016 policy (Senate Bill 277) and vaccine coverage in a quasi-experimental state-level synthetic control analysis and a county-level difference-in-differences analysis. State-level data were included for 45 states from 2011 to 2017, and county-level data from 17 states were obtained from 2010 to 2017.
The researchers found that measles, mumps, and rubella coverage increased by 3.3 percent in California relative to its synthetic control in the postpolicy period in a state-level synthetic control analysis; in addition, nonmedical exemptions decreased by 2.4 percent and medical exemptions increased by 0.4 percent. Overall vaccination coverage increased by 4.3 percent in the county-level analysis, while nonmedical exemptions decreased by 3.9 percent and medical exemptions increased by 2.4 percent. After the policy implementation, from 2015 to 2017, changes in vaccination coverage ranged from −6 percent to 26 percent; larger increases in coverage were seen in counties with lower prepolicy vaccine coverage.
“These study results support the idea that state-level governmental policies to remove nonmedical exemptions can be effective strategies to increase vaccination coverage across the United States,” the study authors write.