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Monday, May 20, 2013

Paper Evaluating the Impact of Potential Malaria Vaccines Published in Malaria Journal

Edward Wenger and Philip Eckhoff's recent publication in the Malaria Journal, A Mathematical Model of the Impact of Present and Future Malaria Vaccines, studies the impact of potential malaria vaccines within the framework of the EMOD model. This individual-based model couples a detailed description of the vector lifecycle with a comprehensive, mechanistic representation of within-host parasite and immune dynamics. The model additionally includes a flexible and powerful framework for configuring and distributing arbitrarily specified campaign interventions to targeted groups of individuals.

The objectives in these studies were to quantify the potential impact of first-generation vaccine candidates as components in multi-intervention elimination strategies, to elucidate which geographical settings in a wide range of transmission intensities and entomological behaviors enable the greatest impact, and to estimate efficacy targets for future vaccines as a function of desired impact.

The first study quantifies the regions in baseline transmission and vector feeding behavior where local elimination is enabled by layering pre-erythrocytic vaccines of various efficacies on top of high and sustained insecticide-treated net coverage.

The second study examines the expected reduction in clinical disease burden as part of an intervention targeted at young children through an expansion of routine immunization. Especially relevant as we begin to consider deploying existing and future vaccines is the question of where they will be most effective. The results quantify the impact over a broad range of transmission intensity, insecticide-treated net coverage, and vector behavior. These results highlight that the maximum-impact setting is one in which the impact of increasing bed net coverage has saturated and where largely outdoor-feeding vectors leave transmission just above the threshold where small perturbations from a vaccine intervention result in large community benefits.

With an encouraging pipeline of vaccine candidates – including the ongoing Phase III trial of RTS,S – mathematical modeling is today an especially important tool to inform decisions and policy going forward.