Although the World Health Organization decided not to recommend the use of RTS,S/AS01, the most advanced malaria vaccine candidate that is in development, in infants within the Expanded Programme of Immunisations (EPI), termination of further development of RTS,S/AS01 would be a loss for malaria elimination efforts according to Roly Gosling of the UCSF Global Health Group’s Malaria Elimination Initiative and Lorenz von Seidlein of the Mahidol-Oxford Tropical Medicine Research Unit, Thailand.
Last year a large Phase III trial of RTS,S/AS01 in both infants aged 6 to 12 weeks and young children 5 to 15 months old, showed that vaccine efficacy waned rapidly and the addition of a booster dose 20 months after the first dose increased protection only slightly. While these findings are disappointing the authors argue that the potential benefit of the high initial protection afforded by the vaccine should not be forgotten and, following further research, the vaccine could potentially be used in intensive malaria elimination strategies in low-endemicity areas to interrupt transmission of the parasite.
The authors conclude, “a new tool for malaria control, RTS,S/AS01, is now available. Although its performance is somewhat disappointing in sub-Saharan African children, the vaccine’s short-term efficacy could potentially be used in other regions and other age groups. Global efforts are currently underway to eliminate malaria, with a special focus in Southeast Asian areas with low malaria incidence and high antimalarial drug resistance. Integration of RTS,S/AS01 into elimination strategies may improve the chances of success.”