The Humanitarian Health Evidence Review

General comments

• This systematic literature review found a lack of high quality evidence for the effectiveness of WASH interventions to address public health outcomes in humanitarian crises. While there is clearly a considerable amount of instructive evidence on WASH interventions in stable and development settings, further evidence specifically in humanitarian settings is required – particularly on feasibility and cost-effectiveness.
• While evidence exists on the effectiveness of WASH interventions in relation to water quality or other WASH indicators, there remain significant gaps in knowledge with regards to the impact of WASH in interventions in relation to health outcomes in humanitarian crises.
• Considering the limited number of studies and the methodological shortcomings of the evidence retrieved, the use of more rigorous and confirmatory study designs (e.g. RCTs) could greatly strengthen the evidence base in the Greater collaboration between WASH professionals and their health and medical counterparts could yield considerable benefits.
• The WASH sector has felt a lack of guidance in the area of measuring the impact of interventions. More assistance (e.g. epidemiologica

Study design

• In order to increase the evidence base of what works well in WASH to improve health outcomes, studies in the future should consider: (i) to include both public health and water quality as outcomes; (ii) to increase the number of humanitarian evaluations studying the effects of WASH interventions on non-diarrhoeal diseases (e.g., trachoma, vector-borne disease); (iii) to characterise uptake and/or behaviour change, not just distribution, of an intervention (including use of direct observation rather than self-reported where possible); (iv) to incorporate methodologically stronger study designs, statistical reporting, and addressing confounding; and (v) to include data on feasibility, acceptability, cost-effectiveness and sustainability.
• More research is needed on WASH behaviour change interventions, particularly with less studied populations (e.g. emerging crises in Syria and Middle-East).
• Research is needed on what study designs (other than RCTs) may provide useful data for WASH and health professionals, including economic studies.
• The methodological rigour of WASH studies needs to be improved so that WASH actors can draw conclusions about comparative effectiveness and efficiency of interventions based on robust findings.
• Economic and anthropological research is needed; what is most cost-effective; what is most feasible; what level of success is acceptable to communities, governments and other actors in relation to health effects seen, as well as money spent?
• Priority should be given to the reported lack of coordination between WASH and health implementing agencies during humanitarian interventions.

Indicators, standards, guidelines

• Sphere indicators are important but difficult to measure in practice. A review of Sphere indicators in the WASH sector is needed.