Vaccinating adolescents against meningococcal disease in Canada: a cost-effectiveness analysis

BACKGROUND: One dose of serogroup C meningococcal conjugate vaccine (MCV-C) at 12 months of age is the most common immunization schedule in Canada, but immunity may wane over time. OBJECTIVES: To assess the cost-effectiveness of a booster dose at 12 years of age with either MCV-C or a quadrivalent ACYW135 meningococcal conjugate vaccine (MCV-4). METHODS: A simulation model for assessing both the direct and indirect effects of vaccination was developed. Age- and serogroup-specific incidence and fatality rates were derived from Canadian surveillance data. Vaccine efficacy was estimated from data from the U.K. and Spain, assuming an age-dependent decline of vaccine efficacy over time. Expected vaccine coverage rates were 90% at 12 months, and 70% at 12 years. Herd immunity was modeled using UK data. Vaccine purchase price per dose was $23 for MCV-C and $70 for MCV-4. Costs and health outcomes were discounted at 3% per year. Results, expressed in 2004 Canadian $ and from a societal perspective, were presented for a steady state situation and a population of 1 million. RESULTS: Under the "no vaccination" base scenario, 5.7 cases of vaccine-preventable meningococcal disease would occur each year. Vaccination at 12 months using MCV-C would reduce the burden of disease by 32%. Adding MCV-C at 12 years of age would reduce the number of cases by 55% at no marginal cost, while using MCV-4 would result in a disease reduction of 78% for a marginal cost of $31000 per QALY gained. Comparing MCV-4 with MCV-C as a booster dose, the incremental cost-effectiveness ratio would be $113000 per QALY. The efficacy of C-MCV vaccination at 12 months and the differential price between the two vaccines were the parameters having the strongest impact on the cost/QALY ratios. Any increase in the incidence of serogroup Y will improve the marginal cost-effectiveness ratio associated with MCV-4. CONCLUSION: Adolescent revaccination would be beneficial. Using C-MCV would be the most cost-effective option, while using MCV-4 would be more effective but would also require more investment.