Published online 17 October 2007 | Nature | doi:10.1038/news.2007.174

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Malaria vaccine hope for Africa's babies

Mozambique trial shows vaccine safe for young infants.

An experimental vaccine has proven 66% effective in infants.WHO

A malaria vaccine trial in Mozambique has shown that the treatment is safe and effective for babies aged just a few weeks. The research brings the vaccine a step closer to widespread use; good news particularly for young infants, who are most at risk of being killed by the disease.

There is still no clinically approved vaccine for malaria, which kills more than a million people each year, many of them babies and most in Africa. The World Health Organization estimates that a child dies of malaria roughly every 30 seconds.

The latest trial raises hopes that the malaria vaccine riddle has been cracked, and that babies can now be protected for the first two years of their lives: a strategy that could prevent millions of deaths.

Details of the trial, published in The Lancet1, are revealed as malaria experts meet this week in Seattle at a conference organized by the Bill & Melinda Gates Foundation to discuss future strategies for tackling the disease.

Infant infections

The latest trial is the first to investigate the effects of an experimental vaccine called RTS,S in very young babies. In 2004, a team led by Pedro Alonso of the Barcelona Centre for International Health Research in Spain showed that RTS,S provides some protection in children aged 1–4 for around 18 months. But malaria experts agree that a vaccine is most useful if given as soon as possible after birth.

So the same group tested the vaccine on 214 infants in Mozambique, where malaria is rife and infection can occur all year round. Half of the children were given RTS,S in a series of jabs at ages 10 weeks, 14 weeks and 18 weeks. The rest of the children were given a vaccine against hepatitis B to ensure that effects seen in the malaria-vaccine group were down to the drug, not the immunization method.

In the vaccinated group, there were 22 cases of infection with the malaria parasite, Plasmodium falciparum, over the 6-month study period — compared with 46 cases in the non-malaria-vaccinated group. Overall, the vaccine was roughly 66% effective, the researchers report.

"The vaccine has partial efficacy, so this will be another tool in the arsenal," says Christian Loucq, director of the PATH Malaria Vaccine Initiative, based in Bethesda, Maryland, which sponsored the research.

Existing anti-malaria measures such as bednets and insecticide spraying of houses will still be essential in combating the disease, Loucq stresses.

Aim for 2013

Although not 100% effective, the new vaccine, developed by GlaxoSmithKline, overcomes several technological hurdles. The complex life cycle of P. falciparum makes malaria a more evasive vaccine target than other types of disease, such as those caused by bacteria or viruses. Loucq admits that researchers still do not really know how the new vaccine works, although they suspect that it encourages the body to create antibodies against the parasite during the first few minutes after infection occurs, before the invading parasite heads for the liver.

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The Malaria Vaccine Initiative is now planning larger trials of RTS,S, with the aim of further demonstrating its usefulness, Loucq says. A trial involving some 16,000 children in seven countries is scheduled to begin in late 2008, and Loucq hopes that it will be approved for widespread use by 2013.

It remains difficult to predict how much the vaccine will cost, and what proportion of available health funding should be spent on it, Loucq says. "At this level, cost estimates are difficult to get," he says. "But I don't think price will be an issue — big organizations will step up." 

  • References

    1. Aponte, J. J. et al. Lancet doi:10.1016/S0140-6736(07)61542-6 (2007).
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