Unraveling the ‘community effects’ of interventions against malaria endemicity: a systematic scoping review

Abstract

Objectives There is an urgent need to maximise the effectiveness of existing malaria interventions and optimise the deployment of novel countermeasures. When assessing the effects of interventions against malaria, it is imperative to consider the interdependence of people and the resulting indirect effects. Without proper consideration of the effects, the interventions’ impact on health outcomes and their cost-effectiveness may be miscalculated. We aimed to summarise how the indirect effects of malaria interventions were analysed and reported.Design We conducted a scoping review.Data sources We searched PubMed, Web of Science and EMBASE.Eligibility criteria We included studies that were conducted to quantify the indirect effects of any interventions for all species of Plasmodium infection.Data extraction and synthesis We used a standardised data collection form to obtain the following information from each record: title, name of authors, year of publication, region, country, study type, malaria parasite species, type of interventions, type of outcomes, separate estimated indirect effect for different conditions, pre-specified to measure indirect effect, secondary analysis of previous study, methods of indirect effects estimation, terms of indirect effects, and if positive or negative indirect effects observed.Results We retrieved 32 articles and observed a recent increase in both the number of reports and the variety of terms used to denote the indirect effects. We further classified nine categories of methods to identify the indirect effects in the existing literature and proposed making comparisons conditional on distance to account for mosquito flight range or intervention density within that range. Furthermore, we proposed using the words community effects or spillover effects as standardised terms for indirect effects and highlighted the potential benefits of mathematical models in estimating indirect effects.Conclusions Incorporating assessment of indirect effects in future trials and studies may provide insights to optimise the deployment of existing and new interventions, a critical pillar in the current fight against malaria globally.