The only approved malaria vaccine in the world offers some protection after three doses, but dwindles in efficacy after seven years, according to a recent study published in The New England Journal of Medicine.
Mosquirix, the vaccine developed by British drug company GlaxoSmithKline, was studied by researchers at the KEMRI-Wellcome Trust research program in Kilifi, Kenya. The seven-year study followed 447 children who received three doses of either Mosquirix or a control vaccine when they were 5 to 17 months old.
During the first year, the risk of contracting the disease in the vaccinated group was 35.9 percent less than the control group. However, after seven years the difference fell to 4.4 percent. Researchers also found that the vaccine's decline in efficacy was fastest in children living in areas with higher than normal rates of malaria.
Philip Bejon, MD, director of the KEMRI program, said this rebound effect may be due to unvaccinated children developing natural immunity against malaria faster than vaccinated children, according to Reuters.
"The results suggest that the implementation of [Mosquirix] will need to be considered carefully and in a way that takes into account different levels of malaria exposure," said Mike Turner, PhD, head of infections at Wellcome Trust — a global health charity that helped fund the study.
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