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 (πi) overestimates protective coverage and underestimates gaps in protective coverage when compared with the proportion of exposure occurring while asleep (πs), 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].