Title : Optimizing oral cholera vaccine allocation: Pre-emptive vs. reactive strategies under uncertainty
Abstract:
Constrained global oral cholera vaccine (OCV) supplies force difficult trade-offs between pre-emptive and reactive deployment in sub-Saharan Africa. To address this, we developed an analytical and simulation framework to optimize OCV allocation to minimize costs that account for costs associated with vaccination and those associated with disease outbreaks. We found that under scarce capacity, the optimal choice depends on comparing reactive effectiveness against pre-emptive effectiveness weighted by outbreak probability; abundant capacity favors pre-emptive allocation augmented by high illness costs. Furthermore, accurate risk targeting under heterogenous risk setting strongly shifts the advantage toward pre-emptive vaccination. Applying a prediction model trained on 2010–2023 surveillance data from sub-Saharan Africa to mixed-strategy simulations, we demonstrated that model-ranked targeting substantially outperforms random allocation. Depending on coverage capacity, the distribution of risks, costs of vaccination and outbreaks, the optimal pre-emptive vaccine fraction ranges widely, 0 to 1. These results provide actionable, data-driven guidance for customizing pre-emptive, reactive, or mixed OCV allocation strategies to specific regional contexts.
