PBM Module 4a Risk-of-bias-tabel
Risk of bias table for intervention studies (randomized controlled trials; based on Cochrane risk of bias tool and suggestions by the CLARITY Group at McMaster University)
| 
			 Study reference (first author, publication year)  | 
			
			 Was the allocation sequence adequately generated? Definitely yes  | 
			
			 Was the allocation adequately concealed? Definitely yes  | 
			
			 Blinding: Was knowledge of the allocated interventions adequately prevented? Were patients blinded? Definitely yes  | 
			
			 Was loss to follow-up (missing outcome data) infrequent? Definitely yes  | 
			
			 Are reports of the study free of selective outcome reporting? Definitely yes  | 
			
			 Was the study apparently free of other problems that could put it at a risk of bias? Definitely yes  | 
			
			 Overall risk of bias If applicable/necessary, per outcome measure LOW  | 
		
|---|---|---|---|---|---|---|---|
| 
			 Loeb, 2022  | 
			
			 Definitely yes Reason: Trial participants were randomly assigned (1:1) to either medical masks or N95 respirators. Participants were randomly assigned centrally by a study statistician who generated the sequence using a computerized random number generator. Randomization was stratified by site in permuted blocks of 4. The randomization scheme was provided by an interactive web response system and performed centrally.  | 
			
			 Definitely yes Reason: Investigators were blinded to the group assignment  | 
			
			 Definitely no Reason: it was not possible to conceal the identity of the medical mask or N95 respirator assignment to the study staff or participants  | 
			
			 Definitely yes Reason: loss to-follow-up was minimal and an ITT-analysis was performed  | 
			
			 Definitely yes Reason: All relevant outcomes were reported, and the trial was registered (ClinicalTrials.gov: NCT04296643)  | 
			
			 Definitely no Reason: Potential acquisition of SARS-CoV-2 through household and community exposure, heterogeneity between countries, uncertainty in the estimates of effect, differences in self-reported adherence, differences in baseline antibodies, and between-country differences in circulating variants and vaccination.  | 
			
			 HIGH  |