Parental Factors Associated With Measles–Mumps–Rubella Vaccination in US Children Younger Than 5 Years

<b>Objectives.</b> To determine the association between parental characteristics and MMR (measles-mumps- rubella) vaccination status of children in the United States. <b>Methods.</b> We conducted a cross-sectional study from July 2023 to April 2024 using a digital health survey via OutbreaksNearMe, weighted to target national population characteristics. We analyzed the responses of 19 892 parents of children younger than 5 years to examine the association between self-reported parental characteristics (i.e., sociodemographics, politics, COVID-19 vaccination status) and children's MMR vaccination rates using logistic regression. <b>Results.</b> Children of parents who received at least 1 dose of the COVID-19 vaccine had higher MMR vaccination rates (80.8%) than did children of unvaccinated parents (60.9%; odds ratio [OR] = 1.84; 95% confidence interval [CI] = 1.68, 2.00). We observed lower MMR vaccination rates among children of parents who identified as Republican versus Democratic (OR = 0.73; 95% CI = 0.64, 0.82), parents on Medicaid or Medicare versus private insurance (OR = 0.85; 95% CI = 0.76, 0.95), and minority (OR = 0.44) versus White (OR = 0.71) parents. We found higher MMR vaccination rates in the Northeast and Midwest United States. <b>Conclusions.</b> Early data indicate that parental sociodemographic characteristics and COVID-19 vaccine status are associated with children's MMR vaccine uptake, emphasizing the need for further investigations into multipronged public health interventions. (<i>Am J Public Health</i>. 2025;115(3):369-373. https://doi.org/10.2105/AJPH.2024.307912).