— By Patricia Reaney

LONDON (Reuters) - A trial of new malaria vaccine will begin among children in Mozambique next week, raising hopes that scientists may one day conquer the disease that kills more African youngsters than any other illness.

About 2,000 children will take part in the trial to see whether the RTS,S/AS02 vaccine made by GlaxoSmithKline Plc protects against the disease that affects three million people worldwide, mostly children under five years old.

A vaccine is seen as the best hope against the disease because the malaria parasite has become resistant to some anti-malarial drugs. If a vaccine is proved effective it will be given to babies along with other childhood immunizations.

RTS,S/AS02 is one of 80 malaria vaccines in development, but, said Dr Pedro Alonso of the University of Barcelona who will conduct the trial, "it is the most promising and the most advanced by far."

"All other vaccines are a number of years behind," he told Reuters, adding that the Mozambique experiment was the only large scale efficacy trial in young African children currently being carried out.

The vaccine had a short term efficacy rate of 71 percent when it was tested in adults in Gambia. Scientists are hoping it will work even better in the youngsters but even a 50 percent effectiveness would be a major advance.

"The burden of malaria is of such magnitude that...if we could reduce by 50 percent the amount of clinical disease and death due to malaria, this would be the most effective vaccine ever deployed," Alonso said.

"The efficacy has to be seen in relation to the burden of the disease," he added, estimating that a 50 percent rate would prevent half a million deaths each year.

He expects results from the trial in 18 months. If it is successful, further tests will be done on infants.

Creating a vaccine against the disease has been a top public health priority. Forty percent of the world's population is at risk of malaria, which kills an African child every 30 seconds.

Vaccine development has been difficult because of the complexity of the mosquito-borne Plasmodium falciparum parasite which has more than 5,000 genes.

The project is a collaborative effort involving the non-profit Malaria Vaccine Initiative (MVI), GSK, the Mozambique Ministry of Health, the University of Barcelona and the Centro de Investigacao em Saude de Manhica (CISM) in Mozambique.

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