Physical interventions to interrupt or reduce the spread of respiratory viruses. Part 2 - Hand hygiene and other hygiene measures: systematic review and meta-analysis.

OBJECTIVE: To assess the effectiveness of hand hygiene, surface disinfecting, and other hygiene interventions in preventing or reducing the spread of illnesses from respiratory viruses. DESIGN: Update of a systematic review and meta-analysis focussing on randomised controlled trials (RCTs) and cluster-RCTs (c-RCTs) evidence only. DATA SOURCES: Eligible trials from the previous Cochrane review, search of the Cochrane Central Register of Controlled Trials, PubMed, Embase and CINAHL from 01 October 2010 to 01 April 2020, and forward and backward citation analysis of included studies. DATA SELECTION: RCTs and c-RCTs involving people of any age, testing the use of hand hygiene methods, surface disinfection or cleaning, and other miscellaneous barrier interventions. Face masks, eye protection, and person distancing are covered in Part 1 of our systematic review. Outcomes included acute respiratory illness (ARI), influenza-like illness (ILI) or laboratory-confirmed influenza (influenza) and/or related consequences (e.g. death, absenteeism from school or work). DATA EXTRACTION AND ANALYSIS: Six authors working in pairs independently assessed risk of bias using the Cochrane tool and extracted data. The generalised inverse variance method was used for pooling by using the random-effects model, and results reported with risk ratios (RR) and 95% confidence intervals (CIs). RESULTS: We identified 51 eligible trials. We included 25 randomised trials comparing hand hygiene interventions with a control; 15 of these could be included in meta-analyses. We pooled 8 trials for the outcome of ARI. Hand hygiene showed a 16% relative reduction in the number of participants with ARI (RR 0.84, 95% CI 0.82 to 0.86) in the intervention group. When we considered the more strictly defined outcomes of ILI and influenza, the RR for ILI was 0.98 (95% CI 0.85 to 1.14), and for influenza the RR was 0.91 (95% CI 0.61 to 1.34). Three trials measured absenteeism. We found a 36% relative reduction in absentee numbers in the hand hygiene group (RR 0.64, 95% CI 0.58 to 0.71). Comparison of different hand hygiene interventions did not favour one intervention type over another. We found no incremental effects of combining hand hygiene with using face masks or disinfecting surfaces or objects. CONCLUSIONS: Despite the lack of evidence for the impact of hand hygiene in reducing ILI and influenza, the modest evidence for reducing the burden of ARIs, and related absenteeism, justifies reinforcing the standard recommendation for hand hygiene measures to reduce the spread of respiratory viruses. Funding for relevant trials with an emphasis on adherence and compliance with such a measure is crucial to inform policy and global pandemic preparedness with confidence and precision.