Early trials of the RTS, S/AS02A vaccine have shown that the vaccine is safe, well tolerated, and can trigger an immune response. In one of the trials, involving over 2000 Mozambican children aged 1-4 years, Pedro Alonso (University of Barcelona, Spain) and colleagues found that after 6 months' follow-up the vaccine reduced the risk of clinical malaria by 30%, delayed time to first infection by 45%, and reduced the risk of severe malaria by 58%. In the latest study the investigators followed-up the children for a further 12 months. They found that the efficacy of the drug did not wane and that protection against clinical malaria lasted for at least 18 months after vaccination. The study shows that the vaccine reduces the risk of clinical malaria by 35% and nearly halves the risk of severe malaria over a period of 18 months.

Professor Alonso states: "Our results show that the RTS,S/AS02A candidate malaria vaccine confers partial protection for at least 18 months against a range of clinical diseases caused by P falciparum in children living in a rural malaria endemic area of African The combination of sustained protection together with substantial prevention of the severe forms of malaria marks RTS, S/AS02A as a promising vaccine candidate and strongly suggests that malaria vaccines have an important role as future public-health instruments."

The publication coincides with a presentation at the Fourth Multilateral Initiative on Malaria Pan-African Malaria Conference 2005 in Yaounde, Cameroon.

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Contact: Joe Santangelo
j.santangelo@elsevier.com
212-633-3810
Lancet
15-Nov-2005