Stresman G, Whittaker C, Slater HC, et al. - Based on the assumption that individuals infected with malaria are clustered within households or neighbourhoods, reactive malaria strategies are designed. Although reactive strategies are widely programmatically implemented, there is little empirical evidence suggesting whether such strategies are appropriate and, if so, how they should be most effectively implemented. Researchers here analyzed data from 208,140 African children obtained from the demographic health survey (DHS) between November 2006 and December 2018 and performed a meta-analysis of 132,590 individuals of all ages from all malaria-endemic settings around the world published between April 2006 and May 2019. Findings from both datasets support clustering of malaria infections in households at all transmission intensities. However, clustering becomes more conspicuous as transmission intensity reduces (ie, a larger proportion of infected individuals within a population are clustered in fewer households). Targeting all household members of index cases with interventions could result in treatment of nearly 75% of all infections in a community once transmission intensity is very low.