A pioneering vaccine can protect a significant proportion of African children against malaria, scientists said on Thursday, boosting hopes that the mosquito-borne disease may one day be conquered.

An effective vaccine is the “holy grail” in the battle against malaria, which makes up to 500 million people sick each year and kills between 1 and 3 million, most of them African children under five.

“This is a really huge breakthrough,” said Melinda Moree, director of the non-profit Malaria Vaccine Initiative, one of the groups behind the clinical trials programme.

“It shows you can impact on disease in kids in Africa. This is the first vaccine that has ever shown that, and that is what makes us really sit up and take notice.”

The goal is to give GlaxoSmithKline Plc’s RTS,S/AS02A shot to babies alongside other childhood immunisations.

But it is not a miracle cure and the need for further tests means it will not reach the market before 2010.

“The results of this trial indicate that an effective vaccine against malaria that could potentially save the lives of millions of children is possible,” Dr Marie-Paule Kieny, of the World Health Organisation, said in a statement.

In a study involving more than 2,000 children in Mozambique aged one to four, the vaccine proved 30 percent effective in preventing all cases of malaria. However, it reduced the risk of getting life-threatening forms of the disease, needing hospital treatment, by 58 percent - enough to save many lives.

Results from the intermediate phase II study are published in The Lancet medical journal, based on six months follow-up after administration of three monthly injections.

Longer studies are now needed to prove the effect does not wear off and that there is no interference with other childhood shots, before final phase III trials in infants get under way.

Those pivotal tests are likely to be conducted in six to eight African countries.

GENETIC COMPLEXITY

GSK’s vaccine is against Plasmodium falciparum, the most severe form of the disease which dominates in Africa. It is the most advanced of some 80 candidates in development.

The shot targets just one stage in the parasite’s life cycle and its success in stopping damage to the liver and red blood cells has taken some scientists by surprise.

Because of the parasite’s genetic complexity, many had doubted a vaccine based on a single antigen would work. The fact it does suggests a multiple shot might be even more effective.

Economically, the new vaccine also breaks new ground because it is the fruit of a new kind of public-private partnership.

Until now, pharmaceutical companies have had little incentive to develop vaccines for diseases that affect only the poor, since they do not provide significant profits.

Under the new model, however, charitable groups such as the Bill & Melinda Gates Foundation provide cash while industry offers help “in kind” in the form of staff and facilities.

A precondition of the arrangement is that any resulting products are sold at low prices in poor countries. If the right balance is struck, however, GSK may still make money.

“We are confident that now all donors are committed to making this vaccine available as soon as possible and also to guarantee a reasonable return to GlaxoSmithKline,” Jean Stephenne, head of GSK’s vaccines business, told reporters.

Each vaccine is likely to cost “a few dollars”, he added.

GSK is not expecting to sell its vaccine to travellers from developed countries since it will not be able to compete with prophylactic drugs that offer almost 100 percent protection.