Potential for improving age-appropriate vaccination coverage by maximizing the 18-month well-child visit

To evaluate potential age-appropriate up-to-date (UTD) vaccination coverage achievable in preschool children if missing vaccinations were administered during a well-child visit at 18 months of age.

Data from the 2004 National Immunization Survey were used in a series of simulations analyzing UTD coverage of the 4:3:1:3:3:1 (diphtheria, tetanus, pertussis/poliovirus/measles-containing vaccine/Haemophilus influenzae type b/hepatitis B/varicella) and 4:3:1:3:3:1 (+) pneumococcal conjugate vaccine (PCV) series. In the models, children not already up-to-date received up to four missing vaccinations during a simulated routine 18-month-old well-child visit.

For the 4:3:1:3:3:1 series, UTD coverage increased from baseline 61 percent (95% confidence interval [CI] = 60-62) to simulated 87 percent (95% CI = 86-88). Among the baseline non-UTD children, 69 percent became up-to-date by simulation with the single visit, of which 44 percent required only one vaccination. For the 4:3:1:3:3:1 (+) PCV series, UTD coverage increased from baseline 38 percent (95% CI = 37-40) to simulated 74 percent (95% CI = 73-75). Among the baseline non-UTD children, 59 percent became up-to-date by simulation with the single visit, of which 47 percent required only one vaccination. UTD coverage increased substantially for all racial/ethnic groups and in all states.

Taking full advantage of the recommended 18-month-old well-child visit to administer missing vaccines would be a strategically timed opportunity to achieve high age-appropriate UTD coverage in preschool children.