New vaccine against falciparum malaria

Malaria vaccine development has been very difficult, partly because of the technical challenges involved, the parasite's complexity and how it evades the immune system. Recently, a new vaccine, RTS,S/AS02, has been developed by GlaxoSmithKline Biologicals. The vaccine prevents the malarial parasite from infecting red blood cells. Malaria is a parasitic disease characterised by high fever, chills and rigors. It is transmitted by the bite of an infected female mosquito. Cerebral malaria, the most dreaded form of the illness, can be fatal. The World Health Organisation estimates there are about 500 million cases of malaria each year. The development of an effective vaccine is thus a major health priority for these countries. Falciparum malaria, one of four different types, affects a greater proportion of the red blood cells than the other types and is a more serious infection. It is a major health problem in India as in most of the tropics and subtropics. Efforts to develop an effective vaccine against malaria during the past three decades have met with only limited success. This new vaccine against P falciparum was tested in a randomised controlled trial to check whether it might provide protection in adults exposed to natural infection. This test was carried out in a rural area of The Gambia. A team of researchers tested three doses of either the new vaccine or the rabies vaccine (control) on 306 men aged 18-45 years. Volunteers were kept under surveillance throughout the malaria transmission season. Blood smears were collected once a week and whenever a volunteer developed symptoms compatible with malaria. The men who received three doses of vaccine were followed up for 15 weeks. The infections occurred significantly earlier in the control group than the group, which received the new vaccine. The researchers are encouraged by the results because it means that they are on the right path and can look forward to developing a better vaccine. Trials of the vaccine will be expanded where it will be tested on children aged one to five years old. It was found that this vaccine was safe and well tolerated. However, a fourth dose significantly boosted protection against infection.

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