Trends in the uptake of pediatric measles-containing vaccine in the United States: A Disneyland effect?

BACKGROUND

The measles outbreak that began in December 2014 at the California Disneyland theme park in the United States (U.S.) received a high amount of media attention. Media attention can influence health-related behaviors. We investigated the effect of the Disneyland outbreak on measles-containing vaccine (MCV) uptake among U.S. children.

METHODS

We used 2012-2017 National Immunization Survey-Child (NIS-Child) data to examine MCV uptake among U.S. children by 19 months of age. We classified MCV coverage among birth cohorts as exposed based on age at the time of the outbreak. A difference-in-differences design with adjustment for categorical birth cohort was implemented in base models to estimate the exposure effect on the outcomes, ≥1-dose MCV coverage or age at first MCV dose, with pneumococcal conjugate vaccination as a control. Primary analyses included this model adjusted for geographic region, maternal education, race/ethnicity, household income, and insurance status, and an exposure-interaction term with maternal education. All analyses included sampling weights.

RESULTS

The study population represented 34,471,357 children. In base models, the Disneyland outbreak was associated with a 1.0% (95% CI: 0.2%, 1.8%) increase in ≥1-dose MCV coverage and a 6.6 (95% CI: 4.8, 8.5)-day decrease in MCV administration age. In primary analyses, the outbreak was associated with a 3.9% (95% CI: 3.1%, 4.8%) increase in ≥1-dose MCV coverage among children of college-educated mothers, and a 3.2% (95% CI: 0.6%, 5.9%) decrease among children of mothers earning less than a high school degree. Decreases in MCV administration age ranging from 5.9 (95% CI: 3.3, 8.5) to 9.1 (95% CI: 6.8, 11.4) days were observed across maternal education categories.

CONCLUSIONS

The Disneyland outbreak was associated with differential effects on MCV coverage by maternal education and decreases in MCV administration age among U.S. children. These findings may provide useful insights to inform methods to address pediatric MCV undervaccination.