Health impact of routine measles vaccination and supplementary immunisation activities in 14 high burden countries: a DynaMICE modelling study

BackgroundWHO recommends [≥]95% population coverage with two doses of measles-containing vaccine (MCV). Most countries used routine services to offer MCV1 and later, MCV2. Many countries conducted supplementary immunisation activities (SIAs), offering vaccination to all persons in a given age range irrespective of prior vaccination history. We estimated the relative impact of each dose and delivery route in 14 high burden countries. MethodsWe used an age-structured dynamic model (DynaMICE), to estimate the health impact of different vaccination strategies on measles susceptibility and burden over 2000-2020. We estimated their incremental impact using averted cases and deaths and their efficiency using number needed to vaccinate (NNV) to avert an additional measles case. FindingsCompared to no vaccination, MCV1 implementation averted 823 million cases and 9.5 million deaths, with a median NNV of 1.41. Adding routine MCV2 to MCV1 further averted 108 million cases and 0.4 million deaths, while adding SIAs to MCV1 led to 249 million averted cases and 4 million deaths. Despite a larger incremental impact, adding SIAs to MCV1 showed reduced efficiency compared to adding routine MCV2, with median NNVs of 6.15 and 5.41, respectively. InterpretationVaccination strategies including non-selective SIAs reach a greater proportion of unvaccinated children and reduce burden more than MCV2 alone, but efficiency is somewhat lower because of the wide age groups included in SIAs. This analysis provides insight to improve health impact and efficiency of measles vaccination. FundingGavi, the Vaccine Alliance, and the Bill & Melinda Gates Foundation (OPP1157270)