Assessment of experimental malaria vaccine induced protection in pre-exposed populations

Abstract

Efforts to control and further reduce morbidity and mortality caused by Plasmodium falciparum infections in all age groups will be substantially strengthened by development of efficacious malaria vaccines in malaria pre-exposed populations. 1 Moorthy VS Newman RD Okwo-Bele J-M Malaria vaccine technology roadmap. Lancet. 2013; 382: 1700-1701 Summary Full Text Full Text PDF PubMed Scopus (1) Google Scholar Vaccine development against parasitic diseases represents a formidable challenge given the complexity of parasite life cycles and the intricate human host–parasite interactions. How to robustly assess vaccine-induced protection during clinical development is one of the key determinants driving successful vaccine development programmes. In the field of P falciparum malaria vaccine development, the availability of controlled human malaria infection (CHMI) model has helped to systematically select vaccine candidates, including the advanced subunit vaccines RTS,S 2 Sauerwein RW Roestenberg M Moorthy VS Experimental human challenge infections can accelerate clinical malaria vaccine development. Nat Rev Immunol. 2011; 11: 57-64 Crossref PubMed Scopus (193) Google Scholar (now recommended by WHO), R21, 3 Datoo MS Natama MH Somé A et al. Efficacy of a low-dose candidate malaria vaccine, R21 in adjuvant Matrix-M, with seasonal administration to children in Burkina Faso: a randomised controlled trial. Lancet. 2021; 397: 1809-1818 Summary Full Text Full Text PDF PubMed Scopus (43) Google Scholar and the whole, live organism-based vaccine, PfSPZ Vaccine, 4 Seder RA Chang L-J Enama ME et al. Protection against malaria by intravenous immunization with a nonreplicating sporozoite vaccine. Science. 2013; 341: 1359-1365 Crossref PubMed Scopus (507) Google Scholar for further clinical development. The PfSPZ Vaccine contains irradiation-attenuated, purified, vialed, cryopreserved sporozoites of P falciparum (strain NF54) and numerous studies have shown the vaccine to be safe and tolerable in east and west African volunteers in a broad range of age groups. 5 Jongo SA Urbano V Church LWP et al. Immunogenicity and protective efficacy of radiation-attenuated and chemo-attenuated PfSPZ Vaccines in Equatoguinean adults. Am J Trop Med Hyg. 2021; 104: 283-293 Crossref PubMed Google Scholar , 6 Jongo SA Church LWP Mtoro AT et al. Safety and differential antibody and t-cell responses to the Plasmodium falciparum sporozoite malaria vaccine, PfSPZ Vaccine, by age in Tanzanian adults, adolescents, children, and infants. Am J Trop Med Hyg. 2019; 100: 1433-1444 Crossref PubMed Scopus (29) Google Scholar Safety and efficacy of a three-dose regimen of Plasmodium falciparum sporozoite vaccine in adults during an intense malaria transmission season in Mali: a randomised, controlled phase 1 trialA three-dose regimen of PfSPZ Vaccine was safe, well tolerated, and conferred 51% vaccine efficacy against intense natural P falciparum transmission, similar to 52% vaccine efficacy reported for a five-dose regimen in a previous trial. Full-Text PDF