Predicted Effects of a New Combination Vaccine on Childhood Immunization Coverage Rates and Vaccination Activities

Introduction: A new combination vaccine, diphtheria-tetanus-acellular pertussis (DTaP)-hepatitis B (HepB)-inactivated poliovirus vaccine (IPV) [DTaP-HepB-IPV], recently became available for use in the US primary infant-vaccination series. Our objectives were to estimate its effects on immunization-coverage rates, vaccination activities, and health-system costs in US dollars (2003 values). Methods: A model was developed and applied to medical records of 775 children born in mid-2001 who received primary care at 32 private pediatrics centers. DTaP-HepB-IPV use was predicted by applying decision rules to selectively substitute it for component vaccines, in compliance with the Advisory Committee on Immunization Practices' minimum age and time interval criteria. The model considered effects of DTaP-HepB-IPV on use of HepB at age <6 weeks, and HepB, HepB-Haemophilus influenzae type B (Hib), Hib, DTaP, and IPV at age 6 weeks to 2 years. Results: At 2 years of age, DTaP-HepB-IPV would increase the proportion of children receiving three or more doses of DTaP (95.6% vs 96.4%; p = 0.02), HepB (91.7% _vs _95.2%; p < 0.001), IPV (90.7% _vs _96.3%; _p < 0.001), and each of these vaccines (86.2% vs 94.6%; p < 0.001), compared with those receiving each component in singular or combination vaccinations other than DTaP-HepB-IPV. Coverage rates would also be increased for recommended doses of all three component vaccines at ages 1 and 11/2 years. At 2 years of age, the use of DTaP-HepB-IPV would also reduce the number of injections (17.3 vs 14.6; p < 0.001), vaccination visits (6.8 vs 6.6; p = 0.006), and administration costs ($US240 vs $US203; p = 0.004), compared with those receiving each component in singular or combination vaccinations other than DTaP-HepB-IPV. Conclusion: DTaP-HepB-IPV use is estimated to improve immunization coverage rates while reducing the number of vaccine injections, vaccination visits, and costs.