Multivariate analysis for the risk of clinical malaria using survey-Poisson regression with the interaction between survey and trial group.

*Incidence rate = new cases/1,000person-semester. *“New stratum 1” = in a sensitivity analysis, clusters were re-assigned to 2 new strata based on the December 2004 parasite rate (New stratum 1≥20%; New stratum2<20%). #Point estimate of the interaction term obtained after exponentiation.