Cairns M, Ceesay SJ, Sagara I, et al. - In these case–control studies, seasonal malaria chemoprevention (SMC), when provided as part of routine national malaria control activities, resulted in induction of a very high level of personal protection against clinical malaria over 28 days post treatment; its efficacy herein was similar to that recorded in clinical trials. For ensuring SMC treatments to remain effective, researchers suggest a possible utility of case–control design employed by national malaria control programs at intervals.

• The case–control studies were conducted in Burkina Faso, Chad, Mali, Nigeria, and The Gambia.

• Children with confirmed malaria at a health facility were included as cases.

• Two controls were chosen for each case from the neighborhood where the case lived.

• SMC record cards were used and caregivers were asked to retrieve the dates of SMC treatments.

• Estimation of the effectiveness of monthly SMC treatment in preventing clinical malaria was done by performing comparison of when cases and controls had most recently received SMC.

• Findings from all 7 case–control studies (2 in 2015 and 5 in 2016) revealed induction of a high level of protection against clinical malaria on receiving SMC.

• During the first 4 weeks after treatment, highest protection was generated.

• Pooled data across the 7 studies revealed a reduction in clinical malaria incidence on average by 88% during the first 4 weeks after SMC treatment.

• In the period 5–6 weeks post administration, lower protection was evident from SMC.