Date of Award
Open Access Thesis
Master of Public Health (MPH)
School of Public Health
Linda M. Niccolai
James L. Hadler
Background: Most early childhood immunizations require 3-4 doses to achieve optimal disease protection. Failure to complete multi-dose vaccine series is an important driver of undervaccination. Our objective was to evaluate factors associated with starting but not completing all multi-dose series in the combined 7-vaccine series.
Methods: Using 2019 National Immunization Survey-Child data, U.S. children ages 19-35 months with provider verified vaccination data were classified in one of three vaccination patterns: (1) completed the combined 7-vaccine series, (2) missing ≥1 vaccine series (i.e., selective vaccination), or (3) all series initiated, but did not complete all multi-dose series (i.e., missing ≥1 dose(s)). Associations between sociodemographic factors and starting but failing to complete all multi-dose vaccine series were evaluated using multivariable logistic regression (pattern 3 vs. 1 and 2). Analyses accounted for the stratified survey design and complex survey weighting.
Results: Among N=16,365 children ages 19-35 months, n=12,390 (72.7%) completed the combined 7-vaccine series, n=1,511 (9.9%) were classified as missing ≥1 vaccine series, and n=2,464 (17.3%) had initiated all vaccine series, but did not complete all multi-dose series. Vaccination coverage for multi-dose series was lower compared to single dose series. 8.2% of all U.S. children needed only one additional dose to complete the combined 7-vaccine series. After adjusting for sociodemographic differences, the strongest associations with starting but not completing all multi-dose vaccine series were geographic mobility (aOR: 1.66, 95% confidence interval [CI]: 1.24-2.23), number of children <18 years of age in the household (two to three: aOR: 1.36, 95% CI: 1.07-1.73; four or more: aOR: 1.93, 95% CI: 1.38-2.70), and lack of insurance coverage (aOR: 3.21, 95% CI: 1.56-6.62), as compared to children who completed the combined 7-vaccine series.
Conclusions: Risk factors for starting but failing to complete multi-dose vaccine series included lower socioeconomic status, moving across state lines since birth, having multiple children in the household, and being uninsured. Increased focus on strategies to encourage multi-dose series completion is needed to decrease rates of undervaccination and eliminate structural or other barriers to vaccination.
Michels, Sarah Yukari, "Factors Associated With Failure To Complete Multi-Dose Vaccine Series Among U.s. Children Ages 19–35 Months, National Immunization Survey-Child, 2019" (2022). Public Health Theses. 2182.
This Article is Open Access