Background: Despite the ACIP’s recommendation that children are routinely vaccinated against 14 diseases by age 2, vaccine completion remains low.1 Furthermore, only 2% to 26% of 2-year-olds receive vaccines at age-appropriate times.2 Combination vaccines reduce some barriers to vaccination; however, the impact of combination vaccines on completion and compliance rates is largely unstudied.
Methods: Using a sample of children aged 24 to 35 months from the 2012 National Immunization Survey, we examined the effect of receiving combination vaccines on completion and compliance rates. Receipt of all doses (completion) and receipt of doses at age-appropriate ranges (compliance) were assessed at 24 months. Vaccine delay was measured by summing the number of days a child was noncompliant. Outcomes (completion, compliance, and delay) were compared between children who received combination vaccines and those who received single-antigen vaccines only.
Results: Approximately 66% of children completed the recommended 4:3:1:3:3:1:4 series[1] and 23% were compliant. The most commonly delayed vaccines were Haemophilus influenza type B and pneumococcal. Among non-compliant children, 43% accumulated more than 6 months of delay. Combination vaccines decreased the likelihood of incompletion, non-compliance, and severe delay of the 4:3:1:3:3:1:4 series by 60%.
Conclusions: Most children are non-compliant, which puts them at high-risk of infection during a vulnerable age. These findings suggest the use of combination vaccines may be a successful strategy in increasing timely receipt of recommended vaccines.
