Researchers have demonstrated that a technique for artificially inducing immunity to malaria appears to offer a longer period of protection than the typically short-lived immunity produced by a previous bout of the infection (Roestenberg M et al. Lancet. 2011;377:1770-1776).
In an open-label study from November to December 2009, researchers from the Netherlands did a follow-up study in 10 volunteers who had previously undergone an immunization procedure involving repeated exposure to infectious mosquito bites while under chloroquine prophylaxis. In the new study, the researchers rechallenged 6 volunteers with the bites of 5 mosquitoes infected with Plasmodium falciparum (4 of the original volunteers did not meet inclusion criteria for reinfections). Four of the 6 previously immunized volunteers were found to be free from infection after this first attempt to reinfect them 2.5 years after immunization.
Friedrich MJ. Preventing Malaria. JAMA. 2011;305(23):2402. doi:10.1001/jama.2011.834