Seasonal malaria chemoprevention introduction is associated with sustained reductions in childhood malaria burden in northern Ghana
TL;DR
Although insecticide-treated net coverage declined during the post-SMC period, malaria burden continued to decrease across both routine facility and household survey data sources, consistent with an association between SMC implementation and reduced malaria burden among children under five in a high-transmission Sahelian setting.
Abstract
Malaria remains a leading cause of morbidity and mortality among children under five in northern Ghana. Transmission in this setting is intense and highly seasonal, with most cases occurring during the rainy season from June to September. Seasonal malaria chemoprevention (SMC), the monthly administration of sulfadoxine-pyrimethamine plus amodiaquine to children aged 3–59 months during peak transmission, was introduced across the Northern Region in June 2019. However, its population-level association with childhood malaria outcomes, after accounting for background trends and climatic variability, had not been comprehensively assessed. Here we combined 10 years of monthly health facility data from 2015 to 2024 with four rounds of nationally representative household survey data from 2014 to 2022. We assessed the association between SMC implementation and childhood malaria outcomes using seasonal autoregressive integrated moving average models with exogenous covariates, incorporating monthly rainfall and temperature, alongside a Bayesian structural time-series counterfactual framework. Compared with the projected counterfactual trajectory, malaria death rates, admission rates, and incidence rates in the post-SMC period were estimated to be 80.3%, 23.0%, and 16.1% lower, respectively. However, because of uncertainty around the counterfactual estimates, these results should be interpreted as suggestive of a possible programme-level contribution rather than definitive evidence of statistically confirmed effects. At the individual level, children surveyed in the post-SMC period had significantly lower odds of malaria infection after adjustment for survey month (adjusted odds ratio = 0.595; 95% confidence interval: 0.470–0.751), with consistently lower predicted malaria probabilities observed across all child age groups. Although insecticide-treated net coverage declined during the post-SMC period, malaria burden continued to decrease across both routine facility and household survey data sources. These findings are consistent with an association between SMC implementation and reduced malaria burden among children under five in a high-transmission Sahelian setting and highlight the importance of maintaining high SMC coverage as part of an integrated malaria control strategy.