Current milestones towards development of a fully deployable anti-malaria vaccine-future hope for malaria-free world: a review

Abstract

Despite novel global measures to combat malaria, the disease remains a considerable healthcare burden especially in resource limited settings. It accounts for over 2 million deaths per year, most of which are among young children and pregnant women. Despite intensive research and development, only one candidate vaccine, radiationattenuated sporozoite (RAS, S) has made considerable progress to phase 3 clinical trials, albeit a documented partial efficacy of 46% against clinical malaria. However, it’s on the road map of becoming the first licensed malaria vaccine with identified potential for development of deployable malaria vaccine. Success of this candidate forms a vital public health tool designed to eradicate global malaria. Parasite antigenic diversity, poor understanding of antimalarial immunity, and lack of immune correlates of protection constitute among the major hindrances of developing an effective malaria vaccine. Current vaccine models such as RAS, S targets Plasmodium falciparum during the preerythrocytic and erythrocytic stages, while a few other interventions direct their activity by blocking transmission against asexual stages, and/or against pregnancy-associated malaria. Recombinant vaccines have initially been designed from antigens containing one or two strains, which represents a significantly small fraction of the genetic diversity of malaria parasites, eventually making it cumbersome for investigators to establish strain-specific efficacy in clinical trials. This current review, therefore, seeks to provide an overview of major achievements in malaria research; highlighting potential applications, confounders while also showcasing future directions that purpose to enhance discovery of safe and effective anti-malaria vaccines.