Figure 4.

Prevented cases and number needed to vaccinate to prevent a measles case under alternative assumptions for early MCV2 introduction and different SIA dose distribution

(A) Prevented cases. (B) Number needed to vaccinate to prevent a measles case. In the sensitivity analysis, we modelled the incremental effect and efficiency of vaccination under the alternative assumptions of MCV2 introduction and SIA distribution. The incremental effects of each of the strategies were compared with the strategy in which MCV1 was already in use. The incremental effects of each of the strategies are compared with the strategy in which MCV1 was already in use. In the main analysis, MCV2 was introduced on the basis of its historical WUENIC coverage (dark blue) and SIAs were distributed with an assumption that 7·7% of children were less likely to be reached by vaccination than the rest of the targeted population (red). The alternative MCV2 assumption indicates early introduction of MCV2 in 2000 with coverage inputs from the appendix (p 9; light blue). Three countries that have not yet introduced MCV2 (ie, Uganda, DR Congo, and Somalia) have missing estimates for the original strategy with MCV1 and MCV2. Two alternative assumptions for SIA distribution were evaluated, including prioritisation of children who had not received any MCV doses (pink) and prioritising children who had been previously vaccinated (dark red). MCV=measles-containing vaccine. MCV1=the first routine dose of measles-containing vaccine. MCV2=the second routine dose of measles-containing vaccine. SIA=supplementary immunisation activity. WUENIC=WHO and UNICEF Estimates of National Immunization Coverage.