Malaria Vaccine

Malaria Vaccine

Malaria vaccines are an area of intensive research. However, there is no effective vaccine that has been introduced into clinical practice.

The global burden of P. falciparum malaria increased through the 1990s due to drug-resistant parasites and insecticide-resistant mosquitoes; this is illustrated by re-emergence of the disease in areas that had been previously malaria-free. The first decade of the 21st century has seen reduction. Though the reasons are not entirely clear, improving socioeconomic indices, deployment of artemisinin-combination drugs and insecticide-treated bednets are all likely to have contributed. There has been a major scaling-up in distribution of malaria control measures particularly since the advent of The Global Fund to Fight AIDS, Tuberculosis and Malaria. It is unclear what the future will hold for disease burden trends. If political will and funding is maintained, the disease burden could drop further; if as in the past funding lapses or clinically significant resistance develops to the main antimalarial drugs and insecticides used then the disease burden may rise again. Early evidence of resistance to artemisinins, the most important class of antimalarials, is now confirmed, having manifested as delayed parasite clearance times in the western region of Cambodia on the border with Thailand. This is also the region where resistance to earlier antimalarial drugs emerged and then subsequently spread throughout much of the world in the case of chloroquine. The Bill and Melinda Gates Foundation has launched a call for the aim of the malaria community to shift from sustained control to eradication. It is agreed that eradication is not possible with current tools and that research and development of new drugs, diagnostics, insecticides and a cost-effective deployable vaccine will be needed to facilitate eradication. There has been a great increase in funding for such research in the 21st century.

Vaccines are often the most cost-effective tools for public health. They have historically contributed to a reduction in the spread and burden of infectious diseases and have played the major part in previous elimination campaigns for smallpox and the ongoing polio and measles initiatives. Yet no effective vaccine for malaria has so far been developed. Despite this, researchers remain hopeful. Optimism is justified for several reasons, the first of these being that individuals who are exposed to the parasite in endemic countries develop acquired immunity against disease and death. Such immunity does not however prevent malaria infection; immune individuals often harbour asymptomatic parasites in their blood. Additionally, research shows that if immunoglobulin is taken from immune adults, purified and then given to individuals that have no protective immunity, some protection can be gained. In addition to this, clinical and animal studies have shown that experimental vaccination has some degree of success when using attenuated sporozites and using the RTS,S/AS01 malaria vaccine candidate.