Estimating the cost of reaching zero-dose children in hard-to-reach areas of Ethiopia: the case of periodic intensification of routine immunization strategy

Ethiopia is home to over 1.1 million zero-dose children. Periodic Intensification of Routine Immunization (PIRI) was introduced to reach zero-dose children in hard-to-reach areas and improve vaccination coverage. However, the costs of implementing PIRI were not well known. We estimated the cost of reaching zero-dose children through PIRI in hard-to-reach regions of Ethiopia by using activity-based, bottom-up micro-costing approach from the health system perspective. Data were collected retrospectively from six districts in the Afar and Somali regions of Ethiopia. We estimated the financial and economic costs of delivering vaccines during the most recent PIRI sessions, implemented between December 2023 and November 2024. The average cost per session of PIRI was disaggregated by activity and resource type, and we calculated the volume-weighted cost per dose and per zero-dose child reached. The financial cost per vaccine dose delivered was $0.29, while the economic cost per dose was $0.46. The financial cost per zero-dose child reached was $4.22, and cost economic per zero-dose child reached was $6.65. Costs varied by region, with the Afar region incurring a significantly higher economic cost of $13.06 per zero-dose child, compared to $4.82 in the Somali region. Districts in the Somali region delivered a higher volume of vaccines, resulting in lower unit costs and demonstrating evidence of economies of scale. The primary cost drivers were per diem and travel allowances, accounting for 54% ($754) of the average cost in Afar and 51% ($917) in Somali. This study offers economic and financial evidence on what it costs to reach zero dose children through PIRI in hard-to-reach areas in Ethiopia. The findings can be used to inform planning and budgeting for future PIRI sessions in Ethiopia and other low- and middle-income countries.