Risk Factors Associated with Children Missing the Fourth Dose of DTaP Vaccination

Background: In 2012, reported pertussis reached the highest number of cases (48,277) in the United States since 1955.
Objectives: Estimate the prevalence of children who missed the fourth dose of DTaP (Diphtheria and Tetanus toxoids and acellular Pertussis vaccine) by parents’ confidences in vaccines and influences from providers, the timeliness of the first through the third dose of DTaP, and selected socio-demographic characteristics; identify the significant risk factors for non-receipt of the fourth dose of DTaP; and evaluate the unadjusted and adjusted risk ratios for missing the fourth dose of DTaP.
Methods: Data from 16,919 children 19–35 months living in the United States included in the 2011 National Immunization Survey were analyzed. Weighted categorical data analysis and multivariable regression in the context of complex sample survey were applied to assess the prevalence and to determine the independent risk factors.
Results: Overall, 14.7% of children missed the fourth dose of DTaP. Children who were late in receiving the third dose of DTaP had significantly higher risk of missing the fourth dose of DTaP than children who were on-time in receiving the third dose of DTaP (adjusted risk ratio (RR) 2.48; 95%CI (1.92, 3.20)). The risk of missing the fourth dose of DTaP was 62% higher among children whose parents reported they didn’t have a good relationship with their child’s health-care providers than children whose parents reported having good relationship. Compared with the risk of missing the fourth dose of DTaP among children whose parents were confident in the value of vaccines, the risk was significantly higher for the children whose parents lacked confidence (adjusted RR 1.41; 95%CI (1.05, 1.89)).
Conclusions: Timeliness in receiving the first through the third dose of DTaP, influences from providers, and parents’ confidence in the value of vaccines are the five significant risk factors for missing the fourth dose of DTaP vaccination. They are all modifiable. Future interventions to improve parental relationships with providers and attitudes toward vaccines could help improve pertussis vaccination coverage.