Encouraging phase II results of a trial to test the efficacy of a malaria vaccine for young children is published in this week's issue of THE LANCET.

Over 1 million people a year die from malaria, many of them being young children. The emergence of resistance to previously cheap and effective drugs and population growth in tropical regions could mean that by the end of the decade half the world's population-around 3.5 billion people- could be living in areas where malaria is transmitted .

The malaria vaccine RTS,S/AS02A has shown promise as a potential vaccine against Plasmodium falciparum malaria (the most severe form of the disease); it acts at the 'pre-erythrocytic stage', ie, before the red blood cells become infected. Pedro L Alonso (Hospital Clinic, University of Barcelona, Spain and Manhia Health Research Center, Mozambique) and colleagues report the phase II findings of the efficacy and safety of the vaccine among young children (aged 1-4 years) in Mozambique.

Around 2000 children were randomly allocated three injections of either the candidate malaria vaccine or other control vaccines. The children studied were in two distinct locations and had a slightly different follow up: for children in the first cohort (around 1600 participants), the study assessed the efficacy of the vaccine in preventing clinical episodes of malaria during a 6-month follow-up. For children in the second cohort (around 400 participants), the study assessed the effect of the vaccine on preventing subsequent new infections.

The risk of developing at least one episode of clinical malaria was reduced by 30% during the 6 months of follow up among children given the malaria vaccine compared with children given control vaccines; 58% fewer children developed severe malaria. In the second cohort, vaccine efficacy for extending tim
'"/>

Contact: Joe Santangelo
j.santangelo@elsevier.com
1-212-633-3810
Lancet
14-Oct-2004