Malaria Vaccine Development: Recent Advances alongside the Barriers

Although malaria control efforts have currently reduced much of the morbidity and mortality, yet malaria remains a hard problem in many parts of Africa. Together with the existing malaria control efforts, an effective malaria vaccine is expected to act as an important weapon to fight against malaria burden. Developing an efficacious malaria vaccine is a top priority in the agenda of global health program. However, the multi-stage life cycle, antigenic variation, and vast genetic diversity of malaria parasites made malaria vaccine development difficult for years. This study was conducted with the aim of reviewing the status of malaria vaccine development through different obstacles in the path. Vaccine trials currently upgraded to yield a partially effective and short-lived immunity with the pre-erythrocytic subunit vaccine, RTS,S/AS01, which is likely to be the first vaccine to be licensed for malaria control and elimination in sub-Saharan Africa. A promising result was also observed in the early trials with parenteral administration of the whole sporozoite vaccine in malaria-naïve adults, where a complete protection against malaria was demonstrated. The subunit vaccines may not develop a strong sterile immunity among the malaria endemic community. Therefore, moving forward to the multi-stage vaccine comprising antigens from the pre-erythrocytic, erythrocytic and sexual stages of parasite lifecycle could be the best tool to neutralize the merozoites emerging from hepatocytes and red blood cells, and to break the sexual stage transmission. Furthermore, deep understanding of the potential vaccine targets and how immunity acts is a key roadmap to develop a fully effective vaccine against malaria.