Clinical and Economic Impact of a Combination Haemophilus influenzae and Hepatitis B Vaccine

BACKGROUND: Compliance with hepatitis B virus (HBV) vaccine remains suboptimal, despite a recommendation by the Advisory Committee on Immunization Practices of the US Public Health Service that all newborns be vaccinated. Although a combined HBV-Haemophilus influenzae type b (Hib) vaccine may improve acceptance of the HBV vaccine, the clinical and economic consequences of this intervention are uncertain. OBJECTIVES: To compare the health impact and cost-effectiveness of the following 2 immunization strategies: current practice of administering HBV vaccine separately (75% compliance) and Hib vaccine alone or as part of a multivalent vaccine (95% compliance); and strategy of delivering a combined HBV-Hib vaccine (95% compliance). DESIGN: A Markov model simulated the natural history of acute and chronic HBV and Hib disease in a cohort of US newborns. Clinical and economic variables were obtained from published reports. RESULTS: The Hib-related outcomes were the same in both strategies, because the efficacy and compliance with Hib vaccine were assumed to be equivalent in both. A 53% reduction in the number of cases of HBV infection with the combination strategy (n = 8541) was estimated when compared with current practice (n = 18 044), along with 205 fewer HBV-related deaths per 1 million infants. Immunization costs of the combination strategy were $11.5 million higher than for current practice ($108.4 million compared with $96.9 million), whereas the cost of HBV-related disease was $4.0 million lower than in current practice. The incremental cost-effectiveness ratio for the combination strategy was $17700 per year of life saved. CONCLUSION: An HBV-Hib vaccine in US infants yields substantial benefits, with a cost-effectiveness ratio that is lower than that of many commonly used medical interventions.