The use of insecticide treated nets (ITNs), and subsequently the new generation of long-lasting insecticide treated nets (LLINs), has been a core malaria prevention strategy for more than two decades, and until 2010, distribution of LLINs targeted biologically vulnerable groups such as pregnant women and children aged less than 5 years. In 2008, due largely to increased funding for malaria control leading to impressive gains in LLIN coverage, the Roll Back Malaria (RBM) Partnership set a more ambitious target of universal coverage of LLINs, defined as universal access to, and use of, LLINs.