The effectiveness of hand hygiene interventions for preventing community transmission or acquisition of novel coronavirus or influenza infections: a systematic review

Background Novel coronaviruses and influenza can cause infection, epidemics, and pandemics. Improving hand hygiene (HH) of the general public is recommended for preventing these infections. This systematic review examined the effectiveness of HH interventions for preventing transmission or acquisition of such infections in the community. Methods PubMed, MEDLINE, CINAHL and Web of Science databases were searched (January 2002–February 2022) for empirical studies related to HH in the general public and to the acquisition or transmission of novel coronavirus infections or influenza. Studies on healthcare staff, and with outcomes of compliance or absenteeism were excluded. Study selection, data extraction and quality assessment, using the Cochrane Effective Practice and Organization of Care risk of bias criteria or Joanna Briggs Institute Critical Appraisal checklists, were conducted by one reviewer, and double-checked by another. For intervention studies, effect estimates were calculated while the remaining studies were synthesised narratively. The protocol was pre-registered (PROSPERO 2020: CRD42020196525). Results Twenty-two studies were included. Six were intervention studies evaluating the effectiveness of HH education and provision of products, or hand washing against influenza. Only two school-based interventions showed a significant protective effect (OR: 0.64; 95% CI 0.51, 0.80 and OR: 0.40; 95% CI 0.22, 0.71), with risk of bias being high ( n = 1) and unclear ( n = 1). Of the 16 non-intervention studies, 13 reported the protective effect of HH against influenza, SARS or COVID-19 ( P < 0.05), but risk of bias was high ( n = 7), unclear ( n = 5) or low ( n = 1). However, evidence in relation to when, and how frequently HH should be performed was inconsistent. Conclusions To our knowledge, this is the first systematic review of effectiveness of HH for prevention of community transmission or acquisition of respiratory viruses that have caused epidemics or pandemics, including SARS-CoV-1, SARS-CoV-2 and influenza viruses. The evidence supporting the protective effect of HH was heterogeneous and limited by methodological quality; thus, insufficient to recommend changes to current HH guidelines. Future work is required to identify in what circumstances, how frequently and what product should be used when performing HH in the community and to develop effective interventions for promoting these specific behaviours in communities during epidemics.