Effect of seasonal malaria chemoprevention on incidence of malaria among children under five years in Kotido and Moroto Districts, Uganda, 2021: time series analysis

Background Seasonal malaria chemoprevention (SMC) refers to monthly administration of full treatment courses of anti-malarial medicine to children <5 years during high malaria transmission seasons. SMC has demonstrated effectiveness in Sahel and sub-Sahel countries in Africa. However, it was not implemented in Uganda until April 2021, when the country began SMC in the highly malaria-endemic Kotido and Moroto Districts. This study assessed the effect of SMC on malaria incidence among children <5 years of age in Kotido and Moroto Districts. Methods An interrupted time-series analysis was conducted using monthly national health data from the Uganda Ministry of Health District Health Information System 2. The monthly data for outpatient (uncomplicated) malaria among children <5 years was extracted for the 52 months before SMC implementation (Jan 2017-Apr 2021) and 8 months during SMC implementation (May-Dec 2021). The monthly incidence of uncomplicated malaria per 1000 children <5 years was computed before and during SMC implementation. Results In Kotido District, malaria incidence was 693/1000 during SMC implementation period, compared to an expected 1216/1000 if SMC had not been implemented. The mean monthly malaria incidence was 87/1000, compared to an expected mean of 152/1000 if SMC had not been implemented. This represents a statistically significant mean monthly change of -65.4 (95% CI = -104.6, -26.2) malaria cases/1000 during SMC implementation, or a 43.0% decline. In Moroto District, malaria incidence was 713/1000 during SMC implementation period, compared to an expected 905/1000 if SMC had not been implemented. The mean monthly malaria incidence was 89/1000, compared to an expected 113/1000 if SMC had not been deployed. This represents a statistically significant mean monthly change of -24.0 (95% CI = -41.1, -6.8) malaria cases/1000 during SMC implementation, or a 21.2% decline. Conclusion Implementation of SMC substantially reduced the incidence of uncomplicated malaria among children <5 years in Moroto and Kotido Districts. Scaling up SMC in other districts with high malaria transmission could reduce malaria on a large scale across Uganda.