Efficacy of RTS,S malaria vaccine declines over seven years

Results from a long-term phase II study of the malaria vaccine RTS,S show that its efficacy falls over time, and that this decline is fastest in children living in areas with higher than average rates of malaria. The findings, published in the New England Journal of Medicine , suggest that the benefits of the vaccine are likely to vary across different populations and highlight the need for more research to determine the most effective way of using RTS,S, which last year became the first ever malaria vaccine to receive a green light from the European Medicines Agency. Overall our study shows that RTS,S can benefit children, but suggests that a fourth dose may be important for sustaining this protection over the long term, and to protect against a potential rebound. Dr Ally Olotu, KEMRI-Wellcome and Nuffield Department of Medicine   - Researchers at the KEMRI-Wellcome Trust Programme in Kilifi, Kenya, followed 447 children who had received three doses of either RTS,S or a rabies (control) vaccine when they were 5 to 17 months old. After seven years, there were 312 children still involved in the study. During the first year, the risk of getting malaria in the vaccinated children was 35.9% less than in the control group, but after seven years this protection fell to 4. In children exposed to the higher than average rates of malaria, there were slightly more cases of the disease (1002 cases) in the vaccinated group compared with the control group (992 cases) five years after vaccination.