Seasonal malaria chemoprevention (SMC) involving monthly administration of antimalarial drugs to chldren under 5 years during the malaria transmission son had high efficacy in clinical trials in areas with seasonal malaria transmission SMC was introduced at primary care health posts in Senegal over a 3-year period, in a process requiring training and community education. What would be the best design to assess the effectiveness of SMC on the incidence of malaria in children identified at the health posts? Seasonal malaria chemoprevention (SMC) involving monthly administration of antimalarial drugs to chldren under 5 years during the malaria transmission son had high efficacy in clinical trials in areas with seasonal malaria transmission SMC was introduced at primary care health posts in Senegal over a 3-year period, in a process requiring training and community education. What would be the best design to assess the effectiveness of SMC on the incidence of malaria in children identified at the health posts