Systematic review only
| First author, year [ref.] | Relevant studies/total studies (n/n) | Population | Intervention | Outcome | Findings |
| Low quality | |||||
| McGuinness, 2018 [24] | 14/14 | Low- to middle-income countries School Childcare centre Household General community# | Hand hygiene (education, promotion and infrastructure) | ARI ILI Laboratory-confirmed viral infection ARI-related sick leave and deaths | Hand-hygiene interventions can reduce ARI morbidity in childcare, school and domestic settings, but depend on setting, intervention target and compliance In childcare settings, there is a reduction in ARI-related sick leave and illness (low–moderate-quality evidence) In school settings, there is a reduction in ARI-related sick leave and laboratory-confirmed influenza (moderate–high-quality evidence) but no reduction in ARI illness (low-quality evidence) In domestic settings, there is reduction in ARI and pneumonia in urban settings (high-quality evidence), no reduction in ARI and pneumonia in rural settings (low-quality evidence) and no reduction in secondary influenza transmission in household settings (moderate-quality evidence) |
| Moncion, 2019 [25] | 16/16 | Household Mass gathering (Hajj) General community# | Hand hygiene | Laboratory-confirmed influenza Possible influenza infection (e.g. ARI, ILI) | Effectiveness of hand hygiene against influenza virus infection and transmission in community settings is difficult to determine due to heterogeneity and poor quality of evidence 6 out of 9 studies (1 out of 2 RCTs, 5 out of 7 observational studies) suggest that hand hygiene reduces laboratory-confirmed or possible influenza infection 2 out of 7 studies find hand hygiene to be effective in preventing laboratory-confirmed or possible influenza infection transmission |
| Smith, 2015 [26] | 6/7 | School Household Assisted-living facility General community# | Hand hygiene | ILI Laboratory-confirmed influenza Evidence of decreased transmission (influenza/ILI attack rates, secondary infections ratios, viral illness severity, mortality rates, healthcare utilisation) | Handwashing appears to be helpful in decreasing viral transmission |
| Facemask | Not able to fully assess, secondary to significant design flaws | ||||
| Combination NPIs (one or more of hand hygiene, facemask, education) | Not able to fully assess, secondary to significant design flaws | ||||
| Education as component of other NPI interventions | An NPI approach with an educational component (education, guidance or advice) appears to be effective in decreasing viral transmission | ||||
| Gargling/oral hygiene | Oral hygiene appears to be helpful in decreasing viral transmission | ||||
| Willmott, 2016 [27] | 13/18 | School (ages 3–11 years) Childcare centre | Hand hygiene | Incidence of respiratory tract infections (composite) Laboratory-confirmed respiratory tract infections School sick leave | Hand hygiene may reduce respiratory tract infection incidence, laboratory-confirmed respiratory tract infection and sick leave |
| Critically low quality | |||||
| Chou, 2020 [28] | 15/39 | School Household Mass gathering (Hajj) General community# | Facemasks | SARS-CoV-1 infection SARS-CoV-2 infection MERS-CoV infection ILI CRI Laboratory-confirmed viral infection/influenza | No studies of mask effectiveness for prevention of SARS-CoV-2 in the community Facemask use compared to control may decrease risk of SARS-CoV-1 infection based on 3 observational studies Facemask use may have no effect on risk of ILI, CRI or laboratory-confirmed virus/influenza for both the index case or contacts, based on 12 RCTs |
| Cowling, 2010 [29] | 5/12 | School General community# | Facemask | ILI Laboratory-confirmed influenza | Some evidence to support that wearing masks or respirators is beneficial in preventing influenza transmission if worn during illness Less evidence to support that wearing masks or respirators has benefit in preventing influenza transmission if worn to prevent infection Note, many studies included in the systematic review had masks as part of a combined hand hygiene and facemask group only |
| Fong, 2020 [30] | 57/101 | School Workplace General community# | School closure in Asia, Europe, America, Africa, and Australia Due to outbreak report or teacher's strike, planned holiday, reactive closure, pre-emptive closure | Effectiveness of school closure (poorly defined) | Planned school closure (holiday) may decrease influenza transmission during closure, but leads to increase after opening Pre-emptive school closure may have a moderate impact in reducing influenza transmission by delaying epidemic peak, affecting mean peak and reducing overall attack rate Reactive school closure effectiveness varies |
| MacIntyre, 2020 [31] | 11/19 | School General community# | Facemasks ± hand hygiene | ILI Laboratory-confirmed influenza Influenza infection (poorly defined) | In community settings, masks appear to be effective with and without hand hygiene, and both together are more protective; interventions appear to be more likely to be more effective if used within 36 h of exposure |
| Mbakaya, 2017 [32] | 8/8 | Developing countries School (ages 6–12 years) | Hand hygiene (education, promotion and infrastructure) | ARI School sick leave | Hand hygiene compared to control decreases ARI (risk ratio 0.77, 95% CI 0.62–0.95) Reduction in school sick leave secondary to ILI is 40% (p<0.0001) |
| Singh, 2020 [33] | 7/8 | School Assisted-living facility Adults and children diagnosed with acute URTI General community# | Nasal wash with isotonic/hypertonic solutions Gargling saline/tea Kunjal/stomach saline wash Steam inhalation | CRI Time to resolution of symptomatic illness Viral shedding Transmission to household contacts Adverse events from treatment Sick leave Antibiotic and URTI medication use | Hypertonic saline gargles and nasal wash may help prevent or improve symptoms of respiratory illness, reduce transmission, reduce need for medication and reduce viral loads in patients with common cold |
| Wang, 2017 [34] | 9/19 | School (ages 4–15 years) | Hand hygiene | Sick leave secondary to respiratory illness | Inadequate evidence to show that hand-hygiene interventions have an effect on ARI-associated sick leave; note, 5 out of 9 studies show hand-hygiene intervention has significant reduction in ARI-associated sick leave compared to control (30.9–52.6% reduction) |
| Warren-Gash, 2013 [35] | 16/16 | School Childcare centre Assisted-living facility Workplace Household General community# | Hand hygiene | ILI ARI Laboratory-confirmed influenza | Hand hygiene interventions have the potential to reduce influenza and ARI, but their effectiveness depends on setting, context and compliance Hand hygiene is associated with a large decrease in influenza and ARI in institutional settings (school) and domestic settings (squatter settlement) (moderate–high-quality evidence) Hand hygiene is associated with a small reduction in ARI in daycare centres (high-quality evidence) and in school and workplaces (lower-quality evidence) Hand hygiene did not prevent secondary influenza transmission in households with index cases (moderate–high-quality evidence) |
ARI: acute respiratory illness; ILI: influenza-like illness; RCT: randomised controlled trial; NPI: nonpharmaceutical intervention; SARS-CoV: severe acute respiratory syndrome coronavirus; MERS-CoV: Middle East respiratory syndrome coronavirus; CRI: clinical respiratory infection; URTI: upper respiratory tract infection. #: general community settings refer to all other community-based settings not fitting into any of the major categories such as school, household, assisted living facility, childcare centre or workplace.