drying materials.45 It is unclear whether the way in which these interventions were resourced affected their acceptability, sustainability or study outcomes: only two study reports state the role of these companies in the study, analysis and report. 25 33 Most reports described the intervention protocol and monitoring, three noted intervention costs24 28 46 but few presented process evaluation data. Most outcome measurement methods could have introduced bias due to poor case definition, use of non-validated tools or self-report (including routine school absence reporting data). Some studies which attempted to validate outcomes (eg, illness) experienced attrition due to the complexity of the process (ref. 41, p.3).
Individual study results
Five of the six studies reporting children’s absence and 8 of the 13 studies measuring children’s illness absence reported an intervention effect (see online supplementary table S2 for study results according to review outcomes). The one study reporting staff illness absence found it was higher among the intervention group53 which may be because the intervention included asking staff not to attend work if they had infection symptoms.
All five studies reporting RT infection incidence showed a reduction, but each applied different outcome definitions. Three reported RT infection symptoms (rhinitis, cough); one53 found a reduction in both, one37 only identified a reduction in observed rhinorrhoea and another33 found no change in cough and a 12% increase in rhinorrhoea episodes (‘standard’ intervention vs control).
Two studies reported GI incidence; one reported a reduction,46 the other did not.53 Only one of three studies recording diarrhoeal symptoms found any effect.37 Two studies reported vomiting outcomes,37 53 only one found an effect.53 Two studies41 45 collecting laboratory results found some evidence of decreased ILI, although in one study this only related to influenza A (ref. 41, Supplemental Digital Content (SDC) 2). Four of five studies reporting children’s behaviour change identified a positive intervention effect.34 37 41 48 All five studies reporting changes in children’s and/or staff hand hygiene knowledge, attitudes and/or beliefs found an intervention effect.34 37 41 51 53
Synthesis of results
Due to study heterogeneity and the generally low quality of study design and of study reporting, coauthors agreed that it could be misleading to present pooled estimates of the effect of interventions using MAs.
DISCUSSION Main findings
We found 18 cluster RCTs investigating the effect of interventions with a hand hygiene component on absence and infection among 3–11-year-old children in educational settings. Individual study results suggest interventions may reduce children’s absence, RT infection incidence and symptoms, and laboratory-confirmed ILI. They may also improve children’s and staff hand hygiene attitudes, knowledge and behaviour. Evidence of impact on GI infection or symptoms was equivocal. Despite updating existing SRs and identifying new studies, individual study results appear to show that there remains equipoise about the effectiveness of hand hygiene in preventing RT and GI infection.
Strengths and limitations of this review
Much has been made of the potential of hand hygiene interventions for reducing infection in this population.11 This review provides a more detailed assessment of such interventions and how promising they might be based on studies which apply the most rigorous, RCT evidence. This review updates existing SRs focused on this population, and our comprehensive search strategy resulted in finding more studies than previous SRs. Findings of this review corroborate existing SRs; that studies have signifi- cant design limitations and poor quality reporting. The quality of reporting in more recently published studies27 28 39 seems to have improved which perhaps indicates the impact of guidance on the reporting of cluster RCTs.20 21 This may result in improved evidence, capable of demonstrating the effectiveness of this important public health issue. Despite identifying new studies, it was not possible to produce meaningful MAs (as earlier SRs have found) due to study heterogeneity, study design limitations and poor quality reporting.
Limitations of this SR include that: we assumed that report titles or abstracts would contain ‘handwashing’ or ‘hand/s’ but they did not; unpublished literature was excluded; some included studies had study populations which included children younger and older than the prespecified review age range; RT and GI infection incidence can vary within the age range included in the review, as can the potential effectiveness of interventions (due to children’s developmental stage); risk of bias assessment was impeded by inadequate reporting. Furthermore, all interventions with a hand hygiene component were included so the impact of hand hygiene cannot be isolated. This review does not distinguish between handwashing with soap or hand sanitiser use even though these methods may have different resource implications and be differentially effective in eliminating certain pathogens.55
What this study adds
While studies are heterogeneous, there is evidence that hand hygiene interventions among primary school-aged children in educational settings may be beneficial, particularly in reducing RT infection incidence. However, this SR highlights limitations of evidence on this crucial public health issue in a key setting with a vulnerable population and the need for improved studies to enable more definitive assessment (eg, MA) of the effectiveness of simple public health interventions to inform practice. We have four recommendations for future research and which may enable future estimates of the pooled effects of such interventions using MA. First, better designed and reported cluster RCTs are required. Investigators should apply guidance20 21 and learn from robust studies39 in order to avoid design flaws (eg, clusters at classroom level) and improve reporting (eg, children’s age, control group conditions). Second, studies should incorporate technical advances for outcome measurement, such as the use of environmental swabs to detect the level of viral and/or bacterial contamination in schools56 which may enable robust, standardised outcome measures instead of using self-report and observations. Third, research should include process evaluation to refine interventions and establish intervention acceptability and fidelity. Studies which have done process evaluations40 57 have identified barriers to hand hygiene including access to adequate sanitary facilities (even in high-income countries), suggesting that provision of hygiene products and education may be insufficient to achieve effective infection prevention and control and more robust studies of complex, multicomponent interventions are required. Fourth, studies should evaluate cost, cost-effectiveness and intervention sustainability in educational settings.