Effect of a solar-powered spatial emanator on malaria prevalence in Uganda (Mossie-GO trial): A double-blinded, cluster-randomised, and placebo-controlled trial

The continued threat of malaria has driven investigations into the efficacy of a range of new tools, including spatial emanators which release active ingredients that can affect mosquito host-seeking vector behaviour and reduce human contact. This study aimed to estimate the effect of a novel solar-powered spatial emanator in reducing the prevalence of malaria in rural and peri-urban settings. The Mossie-GO trial was a prospective, cluster-randomised, controlled trial conducted in Jinja and Buikwe in Eastern Uganda. Fifty-six clusters were randomised at a 1:1 ratio to receive either the spatial emanator with transfluthrin-treated ‘coins’ or an identical device with no-active ingredient. Up to 100 houses per cluster were enrolled. Investigators, field staff, and study participants were masked to cluster allocation. The primary outcome was malaria infection prevalence among children aged ≤5 years at 12 months, compared between intervention and control clusters and adjusted for baseline cluster-level prevalence. The trial was registered with ClinicalTrials.gov (NCT06232954). The baseline-adjusted analysis did not show evidence of lower malaria infection prevalence in intervention clusters compared with control clusters at follow-up. The unadjusted OR for malaria infection was 0.63 (95% CI: 0.29–1.36, p = 0.239), and the baseline-adjusted OR was 0.96 (95% CI: 0.66–1.39, p = 0.813). No significant differences in mosquito density were observed. No serious adverse events were reported and there was no difference in the rate of adverse events between trial arms. The trial did not demonstrate significantly lower follow-up malaria infection prevalence in intervention clusters after adjustment for baseline cluster-level prevalence. Exploratory subgroup analyses reveal some indication of change and should be interpreted as hypothesis-generating. There was also an observed but not significant reduction in human biting rate in intervention households. Large variation in baseline data and between clusters may have limited the power of the study to detect significant results.