The effectiveness of a malaria vaccine that was widely heralded as potentially saving millions of lives is now being questioned by several researchers, including some of The Scientist's own readers.
Among the concerns is that preliminary results for the vaccine, called RTS,S/AS01, were released even though the full results on long-term protection will not be available until 2014. In addition, the results were released only for children 5 to 17 years old, despite the fact that very young infants (between 6 and 12 weeks old) are the target group that would eventually be given the vaccine. When the limited data available for the youngest children is included, the protection rate drops from more than 55 percent to just 34 percent, raising questions about the effectiveness of the vaccine in the youngest group. The vaccine's effectiveness suffers a similar drop when the protection level is recalculated 12 months after getting the vaccine, as opposed to including vaccinations that were more recent. According to a World Health Organization consortium on malaria vaccine efficacy, an effective malaria vaccine must reach a threshold target of 50 percent long-term protection.
Also worrisome is that the vaccine group exhibited higher levels of rare side effects such as seizures and meningitis, although it’s too soon to draw conclusions, Blaise Genton of the Swiss Tropical and Public Health Institute in Basel told Nature.