New data on the duration of efficacy of GlaxoSmithKline’ malaria vaccine candidate, RTS,S/AS02A, in children showed that vaccine remains efficacious over an 18-month observation period.

The findings are published in The Lancet.

CISM ( Centro de Investigação em Saude da Manhiça ) conducted the study in partnership with Mozambique’s Ministry of Health.
Fourteen hundred forty-two children who had received a three-dose regimen of the vaccine in 2003 were followed for continued assessment of safety, immunogenicity, and efficacy.
No further malaria vaccinations were given.

For the 18-month period of follow-up, RTS,S/AS02A was shown to reduce clinical malaria episodes by 35 percent and severe malaria episodes by 49 percent.

“ These results answer an essential question remaining from the release of the six-month efficacy data a year ago,” said Pedro Alonso, lead author of the article, scientific director of CISM, and head of the Center for International Health at the Hospital Clínic of the University of Barcelona. “ The unprecedented response demonstrated in this study is further evidence that an effective vaccine to help control the malaria pandemic, which kills more than one million people a year in developing countries, is very possible.”

The immunogenicity and safety profiles of the vaccine remained promising. In addition, children vaccinated with RTS,S/AS02A were found at the end of the follow-up period to be 29 percent less likely to be infected with the Plasmodium falciparum malaria parasite.

The participants in the current study will continue to be followed, and MVI and GSK -- with CISM and other clinical trial partners in Africa -- will continue clinical development of the RTS,S/AS02A vaccine.

The reported results are from the single-blind follow-up phase of a randomized, double-blind, controlled proof of concept study in children one to four years of age.

The RTS,S/AS02A vaccine candidate uses a recombinant protein that fuses a part of the Plasmodium falciparum circumsporozoite protein with the hepatitis B surface antigen and targets immune responses against the stage injected by mosquitoes.

Source: GlaxoSmithKline, 2005


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