Experimental malaria vaccine protects many children, study shows

Known by the technical name RTS,S, the vaccine was created more than 25 years ago by scientists at Glaxo and the Walter Reed Army Institute of Research by mixing part of the outer protein of the Plasmodium falciparum malaria parasite with a portion of a hepatitis B virus and a chemical that boosts the immune system’s response. Glaxo estimates that it has spent $300 million on the project, and about $200 million more has come from the Seattle-based Bill & Melinda Gates Foundation.

Researchers previously had reported preliminary results from smaller numbers of children in the study in Mozambique, Gabon, Ghana, Tanzania and Kenya, which provided tantalizing evidence that the vaccine was safe and at least partially effective.

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The new report marks the first results from all 15,460 children ages 6 to 12 weeks and 5 to 17 months who received the vaccine or another one for comparison at 11 sites in Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania between March 2009 and January 2011.

A year after the first 6,000 children ages 5 to 17 months received all three doses of the vaccine, the shots reduced the risk of developing high fever and chills from infection with the parasite by 56 percent and the chances of developing a life-threatening case by 47 percent, the researchers reported. When they analyzed data about severe cases among all 15,460 infants and children, including those followed for up to nearly two years, they found that the vaccine was about 35 percent effective.

“This trial represents a powerful example of the high-quality science that is moving us toward controlling and someday even eradicating malaria,” said Christopher Elias, who heads PATH, a private nonprofit organization in Seattle that is organizing the vaccine effort. “We are on track to make history with this malaria vaccine trial.”

The findings were published online by the New England Journal of Medicine with an editorial to coincide with a presentation at a malaria forum in Seattle sponsored by the Gates Foundation.

The vaccine appears to be as safe as others, causing only relatively mild fevers and swelling at the injection site, the researchers said.

They plan to continue to track the children to see how long the protection lasts as well as gather more safety data on infants and how a booster dose affects the longer-term efficacy. Data from 32 months after the third dose should be available by the end of 2014.

Glaxo said it has no plans to try to develop the vaccine for use in adults.

Vasee Moorthy of the World Health Organization called the findings to date a “major scientific achievement.’’

“For the first time, we have confirmation of substantial efficacy against clinical malaria in a very large phase 3 trial of a malaria vaccine,” Moorthy said. “If licensed, this would be the very first human vaccine against a parasitic disease.”