SARS-CoV-2, surgeons and surgical masks

Table 2 Summary of systematic reviews that provided data on the role of facemask use against respiratory viral infection among health care workers

Ref.	Participants	Intervention(s)	Comparator	Outcome	Comment
Jessop et al[28]	Surgeons	PPE including FFP2/3 and simple surgical masks	Nil	Protection using FFP2/3 respirators is reported to last up to 8 h, whereas protection is to last about 30 min for fluid-repellent masks	Narrative synthesis
Samaranayake et al[19]	Dentists	PPE: masks and respirators	Nil	Wearing layered, face-fitting masks/respirators and protective-eyewear can limit the spread of infection among HCWs; combined interventions such as a face mask and a face shield are better than individual ones	Mostly on HCWs in general, not just dentists
Aggarwal et al[49]	Community dwellers	Facemask and hand washing	Nil	There was no significant reduction in ILI either with facemask alone (pooled effect size: −0.17; [CI95%−0.43–0.10]) or facemask with hand wash (pooled effect size −0.09; [CI95%−0.58 to 0.40])
Liang et al[20]	Diverse participants including HCWs	Facemask	Nil	Use of masks by HCWs can reduce the risk of respiratory virus infection by 80% (OR: 0.20 (95%CI: −0.11–0.37)]
Marson et al[22]	Surgeons	Facemask	Nil	The pooled effect of not wearing facemasks was a risk factor for infection RR: 0.77 (95%CI: 0.62-0.97), a case-control study demonstrated an OR of 3.34 (95%CI: 1.94-5.74) if facemasks were not worn by implant surgeons	The use of facemasks by implant surgeons may be beneficial
Sharma et al[25]	All settings including health care settings	Cloth facemask	Medical grade masks	Cloth facemasks show minimum efficacy in source control than the medical grade mask. The efficacy of cloth face masks filtration varies and depends on material type, and other factors
Santos et al[24]	All settings including health care settings	Cloth facemask	Surgical masks and respirators	Cloth masks presented a considerably lower protection factor [1.9 (95%CI: 1.5-2.3)]; surgical and cloth masks reduced the total number of microbes expelled when coughing wearing a mask, while another study found that neither cloth nor surgical masks effectively filtered the virus expelled through coughing	Cloth masks are not recommendedfor HCWs
MacIntyre and Chughtai[23]	Community, HCWs and sick patients	Face masks	Respirators	RCTs in HCWs showed that respirators, if worn continually during a shift, were effective but not if worn intermittently. Medical masks were not effective, and cloth masks even less effective
Chu et al[21]	Health-care and non-health-care settings	Physical distancing, face masks, and eye protection	N95	Face mask use could result in reduction in risk of infection [aOR: 0.15 (95%CI: 0.07-0.34), RD: -14.3% (95%CI: -15.9 to -10.7)], with stronger association with N95 compared to surgical masks (P = 0.09)	Low certainty of evidence
Bartoszko et al[26]	HCWs	Medical masks	N95	Compared with N95 respirators, the use of medical masks did not increase laboratory-confirmed viral respiratory infection [OR: 1.06 (95%CI: 0.90-1.25)]. Only one trial evaluated coronaviruses separately and found no difference between the two groups (P = 0.49)	Low certainty of evidence but only RCTs are included
Chou et al[27]	Health-care and community settings	Surgical, N95, andcloth	N95 or no mask	In health care settings, observational studies found that risk for infection with SARS-CoV-1 probably decreased with mask use and possibly decreased more with N95 mask use. RCTs found, N95 and surgical masks were probably associated with similar risks for ILI and laboratory-confirmed viral infection	Evidence on effectiveness of facemask is stronger in health care than communitysettings

aOR: Adjusted odds ratio; 95%CI: 95% confidence interval; HCW: Health care worker; ILI: Influenza-like illness; OR: Odds ratio; PPE: Personal protective equipment; RCTs: Randomised controlled trial; RD: Risk difference.