Measles transmission dynamics in Nigeria: Risk-stratified projections of reproduction numbers amid vaccine hesitancy and environmental variability

Measles remains endemic in Nigeria despite the availability of a safe and effective vaccine, largely due to persistent immunity gaps, vaccine hesitancy, and uneven immunization coverage across regions. We develop a risk-stratified dynamic model that incorporates heterogeneous vaccine uptake, behavioral hesitancy, waning immunity, and temperature-sensitive transmission dynamics. The model is calibrated using weekly confirmed measles case data from 2024 and used to estimate state-level control reproduction numbers ( R ₀ ) under baseline and elevated temperature scenarios. Our findings reveal a unimodal relationship between temperature and R ₀ , peaking at 12-15 between 22--26°C, consistent with observed measles seasonality. Geospatial projections indicate that most northern states (such as Kano and Kaduna) sustain high transmission (i.e., high R ₀ ) during January–April, driven by seasonal mixing and low vaccine uptake, with warming scenarios (projected 2.5°C increase in temperature) shifting transmission southward. Sensitivity analyses identify transmission intensity, vaccine coverage, and immunity waning as dominant drivers. Simulations of control interventions—such as targeted vaccination, enhanced surveillance, and early case management—demonstrate high impact when prioritized for high-risk populations and timed to seasonal peaks. Wavelet analysis identifies 2.5–8-week epidemic cycles, aligning with school terms and climatic triggers. These results emphasize the need for climate-informed, spatially targeted immunization and surveillance strategies to control measles in Nigeria.