Nonpharmaceutical interventions to prevent viral respiratory infection in community settings: an umbrella review

Hedi Zhao; Sukhdeep Jatana; Jessica Bartoszko; Mark Loeb

doi:10.1183/23120541.00650-2021

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FIGURE 1
Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram for the identification of systematic reviews and meta-analyses. CINAHL: Cumulative Index to Nursing and Allied Health database.

TABLE 1

Inclusion and exclusion criteria

	Inclusion	Exclusion
Population	Community setting (e.g. school, household, workplace, childcare centre, assisted living facility)	Healthcare workers (including dentists, mainly taking place in clinics)
Intervention	Any nonpharmaceutical intervention (e.g. facemask and variations, hand hygiene with soap, sanitiser or education, nasal or oral hygiene with over-the-counter products, school closure)	Pharmaceutical interventions (e.g. prescription medications, vaccines, professional oral hygiene, antiviral agents), surface or object disinfection Population-scale interventions (e.g. mass quarantine, airport screening, lockdowns, travel restrictions)
Comparison	No intervention or control
Outcome	Self-reported or clinically diagnosed ARI, ILI, CRI Laboratory-confirmed influenza	Bacterial infection, fungal infection, parasitic infection
Language	English	Language other than English
Study type	Systematic reviews of interventional, observational, epidemiological studies	Nonsystematic reviews, systematic reviews containing modelling or simulation studies, umbrella reviews, meta-reviews
Time period	1 January 2020 to 31 December 2020	Before 1 January 2020 or after 31 December 2020
Other	Must have at least two contributing authors	Single author, full text unretrievable

ARI: acute respiratory illness; ILI: influenza-like illness; CRI: clinical respiratory infection.

TABLE 2

Systematic reviews and meta-analyses

First author, year [ref.]	Total studies (n)	Relevant studies/total studies in meta-analysis (n/n)	Population	Interventions	Outcome	Findings
Low quality
Chu, 2020 [14]	172	3/44 Observational studies	General community^# Household	Facemask	Probable or confirmed SARS-CoV-1 infection	Facemask use by those exposed to infected contacts decreases the risk of infection (relative risk 0.56, 95% CI 0.40–0.79; low–moderate credibility)
Jefferson, 2020 [10]	67	16/35 Hand hygiene RCTs	School Childcare centre Household Workplace Military (navy) Assisted-living facility Mass gatherings General community^#	Hand hygiene	ARI Laboratory-confirmed influenza Laboratory-confirmed other virus Sick leave	Hand hygiene decreases the composite outcome of ARI, ILI or laboratory-confirmed influenza relative to control (risk ratio 0.89, 95% CI 0.84–0.95; low-certainty evidence) with high heterogeneity Hand hygiene reduces the risk of ARI relative to control (risk ratio 0.84, 95% CI 0.82–0.86; moderate-certainty evidence) Hand hygiene does not reduce the risk of ILI and laboratory-confirmed influenza (risk ratio 0.91, 95% CI 0.63–1.30; low-certainty evidence) Hand hygiene reduces the rate of sick leave compared to control (risk ratio 0.64; 95% CI 0.58–0.71)
				Facemask		Mask results were not differentiated between community and healthcare settings
				Facemask and hand hygiene		Hand hygiene with facemasks does not reduce the risk of ILI (risk ratio 1.03, 95% C1 0.77–1.37) or laboratory-confirmed influenza (risk ratio 0.99, 95% CI 0.69–1.36) compared to control
				Gargling		Gargling does not reduce the risk of viral illness compared to control (risk ratio 0.91, 95% CI 0.63–1.31)
Wong, 2014 [15]	18	10/10 RCTs	Household School Workplace	Hand hygiene	ILI Laboratory-confirmed influenza	Hand hygiene alone compared to control does not demonstrate a significant benefit for ILI (risk ratio 0.86, 95% CI 0.71–1.04) and laboratory-confirmed influenza (risk ratio 0.90, 95% CI 0.67–1.20)
				Hand hygiene and facemask		Hand hygiene with facemask use compared to control is associated with significantly decreased ILI (risk ratio 0.73, 95% CI 0.6–0.89) and laboratory-confirmed influenza (risk ratio 0.73, 95% CI 0.53–0.99)
				Hand hygiene ± facemask		Hand hygiene with or without facemask compared to control is associated with a significant decrease in ILI (risk ratio 0.78, 95% CI 0.68–0.9), but a nonsignificant effect on laboratory-confirmed influenza (risk ratio 0.82, 95% CI 0.66–1.02) Subgroup analysis of less-developed countries for the same interventions and outcomes does not demonstrate statistically significant results
Critically low quality
Abdullahi, 2020 [16]	17	7/7 RCTs and observational studies	Low- to middle-income countries (China, Bangladesh, Thailand) Household School General community^#	Facemask	SARS and influenza incidence	Facemask use demonstrates no significant benefit to the composite of influenza and SARS spread versus control (risk ratio 0.78, 95% CI 0.36–1.67)
				Hand hygiene		Hand hygiene demonstrates no significant benefit to SARS and influenza spread versus control (risk ratio 0.95, 95% CI 0.83–1.08)
				Facemask and hand hygiene		Facemasks with hand hygiene demonstrates no significant benefit to influenza spread versus control (risk ratio 0.94, 95% CI 0.58–1.54)
				Social distancing		Social distancing interventions may slow down the spread of influenza (low-certainty evidence, 9 studies not pooled)
Aggarwal, 2020 [17]	9	8/9 RCTs	Household School	Facemask	Clinically diagnosed influenza or ILI	Facemasks show no significant reduction of ILI compared to control (effect size −0.17, 95% CI −0.43–0.10)^¶
Aggarwal, 2020 [17]	9	8/9 RCTs	Household School	Facemask and hand hygiene	Clinically diagnosed influenza or ILI	Mask and hand hygiene show no significant reduction of ILI compared to control (effect size −0.09, 95% CI −0.58–0.4)^¶
Gera, 2018 [18]	41	8/34 RCTs and non-RCTs	Low- to middle-income countries Individuals, families or communities Children aged <18 years	Hand hygiene	ARI Laboratory-confirmed influenza School sick leave	Hand hygiene compared to control decreases the risk of ARI (risk ratio 0.76, 95% CI 0.59–0.98), 6 studies, moderate-quality evidence Hand hygiene compared to control decreases laboratory-confirmed influenza (risk ratio 0.5, 95% CI 0.41–0.62), 1 study, very low quality evidence Hand hygiene compared to control decreases school sick leave (risk ratio 0.78, 95% CI 0.76–0.8), 4 studies, moderate-quality evidence
Liang, 2020 [19]	21	8/8 RCTs and observational studies	School Mass-gathering (Hajj) Workplace Household General community^#	Facemask	Laboratory confirmed respiratory virus Clinically diagnosed ARI	Facemask use compared to control significantly reduces laboratory-confirmed viral infection by 47% (OR 0.53, 95% CI 0.36–0.79)
Rabie, 2006 [20]	8	8/8 RCTs and interventional studies	School Childcare centre Military (navy)	Hand hygiene	ARI Duration of respiratory illness	Hand hygiene measures lower risk of respiratory infection by 24% (relative risk 0.76, 95% CI 0.6–0.96) Sensitivity analysis excluding one uncontrolled study of hand hygiene measures (n=7) demonstrate decreased risk of respiratory infection by 16% (relative risk 0.84, 95% CI 0.79–0.89); note, studies were of poor quality Sensitivity analysis excluding crossover or poor-quality studies had no significant effect
Rainwater-Lovett, 2014 [21]	37	10 personal protective equipment	Assisted-living facility	Personal protective equipment (hand hygiene, mask, droplet precautions)	ILI with minor variations Laboratory-confirmed influenza All studies required laboratory testing to establish influenza as the cause of the outbreak	Personal protective equipment is not associated with decreased influenza A or B attack rate (OR 0.63, 95% CI 0.33–1.19)
Rainwater-Lovett, 2014 [21]	37	18 social distancing	Assisted-living facility	Social distancing (no new admissions, visitor restriction, ward transfer restrictions, isolation or cohorting)		Social distancing is not associated with decreased influenza A or B attack rate (OR 1.31, 95% CI 0.78–2.18)
Wang, 2020 [22]	15	10/10 observational studies	School Household Mass gathering (Hajj) In-flight setting	Facemask ± hand hygiene	ARI Laboratory-confirmed influenza	Facemask use is not associated with reduced ARI incidence (OR 0.96, 95% CI 0.8–1.15) Subgroup analysis of laboratory-confirmed viral infection (OR 0.82, 95% CI 0.63–1.07) does not demonstrate any benefit Subgroup analysis of self-reported/clinically diagnosed ARI (OR 1.1, 95% CI 0.84–1.45) does not demonstrate any benefit
Xiao, 2020 [23]	18	12/12 hand-hygiene studies 10/10 facemask studies	School Household Mass gathering	Facemask and hand hygiene	Laboratory-confirmed influenza	Facemask use with hand hygiene does not significantly decrease laboratory-confirmed influenza (risk ratio 0.91, 95% CI 0.73–1.13; 6 studies)
				Facemask		Facemask use alone does not significantly decrease laboratory-confirmed influenza (risk ratio 0.78, 95% CI 0.51–1.20; 7 studies)
				Facemask ± hand hygiene		Facemask use with or without hand hygiene does not decrease laboratory-confirmed influenza (risk ratio 0.92, 95% CI 0.75–1.12; 10 studies)
				Hand hygiene		No pooled estimate for hand hygiene alone or with optional facemask use due to high heterogeneity

SARS-CoV: severe acute respiratory syndrome coronavirus; ARI: acute respiratory illness; ILI: influenza-like illness; RCT: randomised controlled trial. ^#: 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. ^¶: the effect size was calculated as log(OR). A negative number represents a protective effect.

TABLE 3

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.

TABLE 4

Meta-analyses only

First author, year [ref.]	Relevant/total studies (n/n)	Population	Intervention	Outcome	Findings
Critically low quality
Aiello, 2008 [36]	13/30	School Childcare centre General community^#	Hand hygiene	Reported or diagnosed respiratory illness	All hand hygiene interventions versus no intervention leads to 21% reduction in respiratory illness (95% CI 5–34%) Benzalkonium chloride-based hand sanitiser is 40% effective versus no intervention Antimicrobial soap with education is the best method

^#: 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.

TABLE 5

Summary of study findings for reducing respiratory viral transmission

First author, year [ref.]	Study type	AMSTAR2 rating	Facemask	Facemask+hand hygiene	Hand hygiene	Social distancing	School closure	Oral hygiene, gargle, or nasal wash
Chu, 2020 [14]	SR+MA	L	Probable or confirmed SARS-CoV-1 relative risk 0.56 (0.40–0.79)	n/a	n/a	n/a	n/a	n/a
Jefferson, 2020 [10]	SR+MA	L	n/a	ILI risk ratio 1.03 (0.77–1.37) Laboratory-confirmed influenza risk ratio 0.99 (0.69–1.36)	Composite risk ratio 0.89 (0.84–0.95) ARI risk ratio 0.84 (0.82–0.86) ILI and laboratory-confirmed influenza risk ratio 0.91 (0.63–1.30) Rate of sick leave risk ratio 0.64 (0.58–0.71)	n/a	n/a	Risk of viral illness risk ratio 0.91 (0.63–1.31)
Wong, 2014 [15]	SR+MA	L	n/a	ILI risk ratio 0.73 (0.6–0.89)	ILI risk ratio 0.86 (0.71–1.04) Laboratory-confirmed influenza risk ratio 0.90 (0.67–1.20)	n/a	n/a	n/a
Abdullahi, 2020 [16]	SR+MA	CL	SARS and influenza spread risk ratio 0.78 (0.36–1.67)	Influenza spread risk ratio 0.94 (0.58–1.54)	SARS and influenza spread risk ratio 0.95 (0.83–1.05)	+	n/a	n/a
Aggarwal, 2020 [17]	SR+MA	CL	n/a	ILI effect size^# −0.09 (−0.58–0.4)	ILI effect size^# −0.17 (−0.43–0.10)	n/a	n/a	n/a
Gera, 2018 [18]	SR+MA	CL	n/a	n/a	ARI risk ratio 0.76 (0.59–0.98) Laboratory-confirmed influenza risk ratio 0.5 (0.41–0.62) School sick leave risk ratio 0.78 (0.76–0.8)	n/a	n/a	n/a
Liang, 2020 [19]	SR+MA	CL	Viral infection OR 0.53 (0.36–0.79)	n/a	n/a	n/a	n/a	n/a
Rabie, 2006 [20]	SR+MA	CL	n/a	n/a	Respiratory infection relative risk 0.76 (0.6–0.96)	n/a	n/a	n/a
Rainwater-Lovett, 2014 [21]	SR+MA	CL	n/a	Influenza A or B attack rate OR 0.63 (0.33–1.19)^¶	n/a	Influenza A or B attack rate OR 1.31 (0.78–2.18)	n/a	n/a
Wang, 2020 [22]	SR+MA	CL	ARI OR 0.96 (0.8–1.15) Laboratory-confirmed viral infection OR 0.82 (0.63–1.07) Self-reported and clinically diagnosed ARI OR 1.1 (0.84–1.45)	n/a	n/a	n/a	n/a	n/a
Xiao, 2020 [23]	SR+MA	CL	Laboratory-confirmed influenza risk ratio 0.78 (0.51–1.20)	Laboratory-confirmed influenza risk ratio 0.91 (0.73–1.13)	n/a	n/a	n/a	n/a
McGuinness, 2018 [24]	SR	L	n/a	n/a	++	n/a	n/a	n/a
Moncion, 2019 [25]	SR	L	n/a	n/a	+	n/a	n/a	n/a
Smith, 2015 [26]	SR	L	n/a^§	n/a^§	++	n/a	n/a	++
Willmott, 2016 [27]	SR	L	n/a	n/a	++	n/a	n/a	n/a
Chou, 2020 [28]	SR	CL	−	n/a	n/a	n/a	n/a	n/a
Cowling, 2010 [29]	SR	CL	+	n/a	n/a	n/a	n/a	n/a
Fong, 2020 [30]	SR	CL	n/a	n/a	n/a	n/a	++	n/a
MacIntyre, 2020 [31]	SR	CL	++	++	n/a	n/a	n/a	n/a
Mbakaya, 2017 [32]	SR	CL	n/a	n/a	++	n/a	n/a	n/a
Singh, 2020 [33]	SR	CL	n/a	n/a	n/a	n/a	n/a	+
Wang, 2017 [34]	SR	CL	n/a	n/a	+	n/a	n/a	n/a
Warren-Gash, 2013 [35]	SR	CL	n/a	n/a	++	n/a	n/a	n/a
Aeillo, 2008 [36]	MA	CL	n/a	n/a	Reduction in respiratory illness 21% (5–34%)	n/a	n/a	n/a

Includes study type and AMSTAR (A Measurement Tool to Assess Systematic Reviews) 2 rating. Data are presented as ratio value (95% CI), unless otherwise stated. SR: systematic review; MA: meta-analysis; SARS-CoV: severe acute respiratory syndrome coronavirus; n/a: not applicable; ILI: influenza-like illness; ARI: acute respiratory illness; L: low quality; CL: critically low quality; ++: findings suggest positive effect; +: findings suggest potential positive effect; −: findings suggest no effect/neutral effect. ^#: effect size=log(OR); ^¶: personal protective equipment as an intervention was categorised as masks+hand hygiene; ^§: no clear summary statement and not able to fully assess, because of methodological flaws in studies included in systematic review.

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