The Spread of Infectious Diseases in Migration Routes Between Caravans and Resident Communities: Modelling Yellow Fever in Central America

Objectives To investigate the impact of yellow fever (YF) vaccination in the context of an outbreak and its association with migration, by assessing the effects of herd immunity in endemic communities and caravans, and its potential spread to other subsequent at-risk, disease-free communities in the migratory route. Methods We use a SEIRV-SEI compartmental deterministic model for humans and vectors and numerical simulations applied to three coupled populations - caravans, endemic and disease-free communities. Two scenarios are evaluated with different vaccination coverage levels at endemic communities and in caravans. Results When communities endemic to YF are the source of migration, herd immunity is critical, but vaccinating caravans is by far the most significant intervention to protect migrants and disease-free communities upwards from the risk of YF introduction. Conclusion Preventing outbreaks of climate-sensitive infectious diseases in the context of migration must be a joint effort of common interest. Maintaining vaccination coverage at recommended levels combined with the continued effort to vaccinate people on the move is the only intervention that can prevent a health crisis. Therefore, vaccination against climate-sensitive diseases should be considered climate adaptation.