A first-ever malaria vaccine tested in children in sub-Saharan Africa cut the risk of infection with malaria by about half — a remarkable achievement, considering there has never been a vaccine against a human parasite before, or against malaria, which infects millions of children each year.
Scientists working in a public-private partnership involving GlaxoSmithKline Biologicals, the PATH Malaria Vaccine Initiative and the Bill and Melinda Gates Foundation, at 11 sites in Africa, reported that the experimental vaccine known as RTS,S was 56% effective in protecting children aged 5 to 17 months from infection with malaria a year after immunization. The vaccine was also 47% effective in preventing severe cases of the disease.
The trial is not complete. Researchers are continuing to follow a younger group of infants, aged 6 to 12 weeks, who are being vaccinated as well. This group would be the target population for the malaria vaccine, should it prove effective, since they take part in routine public health vaccination programs. Both age groups will be followed for nearly three years to track malaria infections and to see how long protection lasts; researchers are also collecting additional safety data in infants. The trial, which involves a total of 15,460 children, will be completed in 2014.
While the initial findings were encouraging, public health officials now have to decide whether they are strong enough to warrant widespread immunization where malaria is endemic. Generally, vaccines against childhood infections such as measles and rotavirus reach efficacy rates of 70% to more than 90%.