Speaker
Description
In 2024, Brazil faced its worst dengue epidemic, with 6 million cases and 5,000 deaths. A shift toward higher mortality among the elderly challenges WHO strategies prioritizing children. As immunity varies across Brazil’s geography, a "one-size-fits-all" vaccination approach may not be optimal.
We reconstructed state- and age-specific immune profiles across Brazil by fitting an age-structured catalytic model, which assumes a piecewise constant force of infection, to surveillance data (2000–2024). These profiles, accounting for historical force of infection and demographics, were integrated into an SIR-type transmission model. We simulated vaccine strategies to project disease burden and evaluate impact under supply constraints.
Our model revealed substantial spatial heterogeneity in immunity. In hyperendemic states like Rio de Janeiro, most elderly have had multiple infections. In southern states like Santa Catarina, many remain at risk. While child-centric strategies reduce DALYs, targeting the elderly in regions with lower historical exposure yields larger mortality reductions.
Findings emphasize that dengue vaccination must be tailored to local immunity. In regions where older adults lack cumulative exposure, including them in programs significantly mitigates severe disease and death. This research provides a data-driven framework for sub-national vaccine prioritization.
