Malaria Vaccines: Recent Advances and New Horizons
Modern malaria vaccine development began with seminal studies in mice using irradiated sporozoites (Nussenzweig et al., 1967). Although there is still no licensed product over 50 years later, it is important to remember the scale of the scientific and technical challenges facing those who develop vaccines against such a complex eukaryotic parasite. Moreover, steady progress is being made, especially with regard to breakthroughs in our understanding of the cellular and molecular mechanisms mediating protection in animal models and humans. The revised Malaria Vaccine Technology Roadmap to 2030 (Moorthy et al., 2013) now calls for a next-generation vaccine to achieve 75% efficacy over 2 years against P. falciparum and/or P. vivax (in an era of renewed global interest toward malaria elimination and eradication), while also retaining its original 2015 “landmark” goal of a first-generation vaccine with protective efficacy of >50% lasting more than 1 year. Achieving this next-generation vaccine goal will necessitate building on the success of current pre-erythrocytic subunit and whole sporozoite-based vaccines, as well as new strategies to add blood-stage or transmission-blocking immunity. Here we review the progress and prospects for a diverse range of approaches targeting different stages of the P. falciparum parasite’s complex life cycle (Figure 1), before discussing those in development for P. vivax.