Delayed or Absent First Dose of Measles, Mumps, and Rubella Vaccination

How have factors associated with late MMR (measles, mumps, and rubella) vaccination or nonvaccination changed since the COVID-19 pandemic?In this cohort study, 321 743 infants were followed up for MMR vaccinations by 2 years of age. Timely MMR receipt decreased by 3 percentage points from 2021 to 2024; the factors most strongly associated with not receiving MMR by 2 years of age were late receipt of standard 2- and 4-month vaccines.This study suggests that, among children with regular access to care, those late on 2- and 4-month immunizations are significantly more likely not to receive MMR vaccination by 2 years, highlighting the importance of early intervention for children deviating from the vaccine schedule.

Corresponding Author: Nina B. Masters, PhD, MPH, Truveta Research, Truveta Inc, 1745 114th Ave SE, Bellevue, WA 98004 (ninam@truveta.com).

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