Figure 4
Comparative evaluation of two alternative measures of the upper limit for the level of protection an insecticide treated net (ITN) can provide from the contrasting perspectives of coverage achieved by a vector control programme versus coverage gaps in a vector elimination programme. The proportion of exposure to mosquito bites which occurs while humans are indoors (Ï€i) overestimates protective coverage and underestimates gaps in protective coverage when compared with the proportion of exposure occurring while asleep (Ï€s), which is considered a more accurate indicator of protective coverage by an ITN because people rarely use one unless they are both indoors and asleep [77].