Key Concepts and Terms Used in this Paper Cost per additional dose for intervention: Additional intervention cost of providing another dose (calculated by dividing the extra cost by additional vaccine doses administered). Cost per intervention: Total cost of implementing an intervention (calculated by adding the value of the cost categories together). Cost per percentage change in immunization coverage: Cost divided by additional percent change in immunization coverage. Cost per person reached: Intervention cost divided by number of persons reached. Incremental cost-effectiveness ratio (ICER): Measure that summarizes the cost-effectiveness of an intervention (ratio of costs of intervention divided by effectiveness measure—such as deaths or disability-adjusted life years (DALYs) averted). Zero-dose child: Child that has not received the first dose of the DTP-containing vaccine.