The Cost-Effectiveness of Supplementary Immunization Activities for Measles: A Stochastic Model for Uganda

Abstract

Supplemental Immunization Activities (SIAs) have become an important adjunct to measles control efforts in countries that endeavor to achieve higher levels of population immunity than can be achieved in a growing routine immunization system. Because SIAs are often supported with funds that have alternative uses, decision makers need to know how cost-effective they are compared with other options. This study integrated a dynamic stochastic model of measles transmission in Uganda (2010-2050) with a cost model to compare a strategy of maintaining Uganda's current (2008) levels of the first dose of routine measles-containing vaccine (MCV1) coverage at 68% with SIAs with a strategy using the same levels of MCV1 coverage without SIAs. The stochastic model was fitted with parameters drawn from district-level measles case reports from Uganda, and the cost model was fitted to administrative data from the Ugandan Expanded Program on Immunization and from the literature. A discount rate of 0.03, time horizon of 2010-2050, and a societal perspective on costs were assumed. Costs expressed in US dollars (2010) included vaccination costs, disease treatment costs including lost productivity of mothers, as well as costs of outbreaks and surveillance. The model estimated that adding on triennial SIAs that covered 95% of children aged 12-59 months to a system that achieved routine coverage rates of 68% would have an incremental cost-effectiveness ratio (ICER) of $1.50 ($US 2010) per disability-adjusted life year averted. The ICER was somewhat higher if the discount rate was set at either 0 or 0.06. The addition of SIAs was found to make outbreaks less frequent and lower in magnitude. The benefit was reduced if routine coverage rates were higher. This cost-effectiveness ratio compares favorably to that of other commonly accepted public health interventions in sub-Saharan Africa.