Perceived Efficacy and Acceptability of a Spatial Repellent for Malaria Control in Western Kenya: Lessons from a Qualitative Social Science Study Conducted in Conjunction with an Epidemiological Efficacy Trial

BackgroundKenyans experienced over 3 million malaria cases in 2023. Insecticide resistance and changing mosquito behavior have reduced effectiveness of insecticide-treated nets (ITNs) and indoor residual spraying (IRS). Spatial repellents (SRs) show promise for malaria control. This social science study, nested within the Advancing Evidence for Global Implementation of Spatial Repellents (AEGIS) clinical trial in Kenya, explored SR acceptability and perceived efficacy. MethodsWe used modified trials of improved practices (TIPs) to assess participant response to Mosquito Shield, a transfluthrin-impregnated SR. We conducted structured observations and semi-structured interviews at 16 intervention and 14 control compounds during five visits over the 24-month clinical trial. We remained blinded to study assignment throughout data collection then analyzed data by study arm after unblinding. ResultsBoth intervention and control participants reported reduced mosquito activity inside homes after initial installation. Over time, most intervention participants reported continued efficacy. Controls, who received identical-looking placebo products, reported decreased efficacy. In both arms, participants mentioned discontinuing ITN use. Closely tied to perceived efficacy, acceptability was also influenced by installation method, number of units required, replacement interval, and perceived community opinion. Discussion/ConclusionSRs seem likely to be accepted in this setting when perceived as effective and installed satisfactorily. National programs considering SR distribution should anticipate decreased ITN use and emphasize that SRs are meant to complement, not replace, existing interventions. SR-related communication should stress proper product use to maximize efficacy. Decreased expenses for products like mosquito coils might incentivize adoption. This study illustrates the value of social science research parallel to an efficacy trial.