What is the malaria vaccine?

Definition

Malaria vaccine is a preparation designed to provide immunity against
infection by the parasite Plasmodium, which
leads to malaria.

Background

Malaria is caused by four species of Plasmodium: P. falciparum, P. vivax, P. malariae, and P. ovale. P. falciparum causes about 90 percent of malaria cases and is responsible for the most deaths, particularly in Africa. It is estimated that 3 billion people are at risk for malaria exposure. About 500 million people suffer from malaria worldwide, and 1 million children in Africa die each year from the disease.

Plasmodia are transmitted by the
Anopheles mosquito; the incubation period lasts between seven and
thirty days, depending on the Plasmodium species transmitted.
Symptoms of malaria include shivering, fever, headache, vomiting, and sweating.
Severe malaria can involve such symptoms as impaired consciousness,
seizures, coma, anemia,
pulmonary
edema, and cardiovascular collapse.

Vaccine Status

Preventing malaria infection is a top priority for many health and research
organizations around the world, as they are trying to establish vaccines to
protect against the disease. No commercially available vaccine for
malaria exists, despite decades of research on the topic. Many researchers are
focusing on developing vaccines against P. falciparum, while a
few groups are working on a vaccine for P. vivax. The life cycle
of P. falciparum is quite complex, as it provides several stages
on which to focus vaccine development.

The most advanced vaccine is RTS,S, which has been studied in phase-three trials in several countries in sub-Saharan Africa since 2009; the phase-two trial for this drug showed 30 to 50 percent efficacy in reducing malaria in infants and children. Based on these results, it appears that the vaccine will only partially protect those immunized.

Another promising vaccine is FMP2.1/AS02A, which has shown efficacy in children in Mali. Numerous clinical trials have attempted to select safe, effective vaccines. Because of the complexity of the parasite’s life cycle, it is likely that multiple types of vaccines will be necessary to interrupt that life cycle.

Impact

A viable, disease-preventing malaria vaccine has the potential to save millions of lives by providing protection against Plasmodium infection.

Bibliography

Crompton, Peter D., Susan K. Pierce, and Louis H. Miller. “Advances and Challenges in Malaria Vaccine Development.” Journal of Clinical Investigation 120 (2010): 4168-4178.

Enayati, A., and J. Hemingway. “Malaria Management: Past, Present, and Future.” Annual Review of Entomology 55 (2010): 569-591.

Mahamadou, A. Thera, et al. “Safety and Immunogenicity of an AMA1 Malaria Vaccine in Malian Children.” PLoS 5 (2010): e9041.

Sherman, Irwin W. The Elusive Malaria Vaccine: Miracle or Mirage? New York: ASM Press, 2009.