TABLE 5

Summary of study findings for reducing respiratory viral transmission

First author, year [ref.]Study typeAMSTAR2 ratingFacemaskFacemask+hand hygieneHand hygieneSocial distancingSchool closureOral hygiene, gargle, or nasal wash
Chu, 2020 [14]SR+MALProbable or confirmed SARS-CoV-1 relative risk 0.56 (0.40–0.79)n/an/an/an/an/a
Jefferson, 2020 [10]SR+MALn/aILI 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/an/aRisk of viral illness risk ratio 0.91 (0.63–1.31)
Wong, 2014 [15]SR+MALn/aILI 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/an/an/a
Abdullahi, 2020 [16]SR+MACLSARS 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/an/a
Aggarwal, 2020 [17]SR+MACLn/aILI effect size# −0.09 (−0.58–0.4)ILI effect size# −0.17 (−0.43–0.10)n/an/an/a
Gera, 2018 [18]SR+MACLn/an/aARI 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/an/an/a
Liang, 2020 [19]SR+MACLViral infection OR 0.53 (0.36–0.79)n/an/an/an/an/a
Rabie, 2006 [20]SR+MACLn/an/aRespiratory infection relative risk 0.76 (0.6–0.96)n/an/an/a
Rainwater-Lovett, 2014 [21]SR+MACLn/aInfluenza A or B attack rate OR 0.63 (0.33–1.19)n/aInfluenza A or B attack rate OR 1.31 (0.78–2.18)n/an/a
Wang, 2020 [22]SR+MACLARI 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/an/an/an/an/a
Xiao, 2020 [23]SR+MACLLaboratory-confirmed influenza risk ratio 0.78 (0.51–1.20)Laboratory-confirmed influenza risk ratio 0.91 (0.73–1.13)n/an/an/an/a
McGuinness, 2018 [24]SRLn/an/a++n/an/an/a
Moncion, 2019 [25]SRLn/an/a+n/an/an/a
Smith, 2015 [26]SRLn/a§n/a§++n/an/a++
Willmott, 2016 [27]SRLn/an/a++n/an/an/a
Chou, 2020 [28]SRCL−n/an/an/an/an/a
Cowling, 2010 [29]SRCL+n/an/an/an/an/a
Fong, 2020 [30]SRCLn/an/an/an/a++n/a
MacIntyre, 2020 [31]SRCL++++n/an/an/an/a
Mbakaya, 2017 [32]SRCLn/an/a++n/an/an/a
Singh, 2020 [33]SRCLn/an/an/an/an/a+
Wang, 2017 [34]SRCLn/an/a+n/an/an/a
Warren-Gash, 2013 [35]SRCLn/an/a++n/an/an/a
Aeillo, 2008 [36]MACLn/an/aReduction in respiratory illness 21% (5–34%)n/an/an/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.