Enlarge Image Dampened hopes. Ally Olotu (right) with a malaria vaccine trial participant and his mother. New results show that the vaccine's protection wanes over time. Credit: John-Michael Maas/Darby Communications There is more cautionary news for the world's most advanced malaria vaccine. A new study in Kenyan children shows that its protection wanes over time, dropping to near zero after 4 years. The results, published in tomorrow's issue of The New England Journal of Medicine, are another strike against the chances that the vaccine will be widely used in its current form. The vaccine, called RTS,S, is the only...