GlaxoSmithKline ($GSK) has added a fresh set of weak results for its experimental malaria vaccine. In a mid-stage study involving more than 400 children in Kenya investigators say that the RTS,S vaccine delivered a 43.6% efficacy rate in the first year and then plunged, falling to zero by the fourth year. And the children most likely to be exposed to malaria were the ones who lost protection at the fastest rate.
Calculated over the full four years, the vaccine registered only a 16.4% efficacy rate. "The results are kind of disappointing because we'd all like to see a malaria vaccine that has closer to 80 percent or 100 percent efficacy," malaria researcher Christopher Plowe, who was not involved in the RTS,S trial, told Reuters.
"The efficacy came back lower than we had hoped, but developing a vaccine against a parasite is a very hard thing to do," said Bill Gates, co-founder of the Bill & Melinda Gates Foundation, according to The Guardian.
Investigators already found out that the vaccine has an even worse efficacy rate in infants, guarding only a third of 6 to 12-week-old children from falling victim to malaria in a large Phase III. This new study underscores a poor response among the target population, though more large-scale Phase III studies are being planned to assess the vaccine, and possibly search for an improved jab.
The research team also cautioned against being too pessimistic. Malaria kills millions of people each year, and any vaccine, even one offering only partial immunity in the target community, would be a big step forward.