Authors

A Bompard¹; D F Da³; ⁴; S YerbangaT LefevreM Kapulu⁵; S Biswas⁵; A CohuetT Churcher¹;  ¹ Imperial college;  ² IRD-MIVEGEC, France;  ³ IRSS, Bobo-Dioulasso, Burkina Faso;  ⁴ IRSS, Bobo-Dioulasso;  ⁵ Jenner Institute, University of Oxford

Discussion

Transmission blocking vaccines (TBVs) against malaria are intended to induce immunity against the stages of the parasites which infect mosquitoes. Used within a community they protect the neighbourhood of vaccinated individuals and could be a key tool for malaria elimination. Various TBV candidates are currently under evaluation. Their efficacy at reducing the number of infectious mosquitoes may depend both on antibody titre and on the level of parasite exposure, which vary between endemic settings and is hard to control in experimental settings. We present an original modelling work based on direct membrane feeding assay experiments for establishing this 3D relationship, a crucial step to understanding TBVs long-term effectiveness. Efficacy estimates are generated from 2 candidates (against Pfs230 and Pfs25), allowing their respective strengths and weaknesses at different titres and exposures to be identified. Results indicate a strong relationship between exposure and efficacy for both antibodies, but also differences that might impact their effectiveness depending on the setting. To approach the biological processes between those differences, we explore the relationship between transmission reduction and exposure and between exposure and prevalence for both TBVs. This work procures a comprehensive method for evaluating TBV candidates and can be combined with Phase II clinical trial data to predict their public health benefit in different endemic settings.