Rapid review of the effects of cloth and medical masks for preventing transmission of SARS-CoV-2 in community and household settings.

Chetty, T; Ramokolo, V; Rees, K; Kredo, T; Balakrishna, Y; Mathews, C; Siegfried, N

BACKGROUND Evidence on mask use in the general population is needed to inform SARS-CoV-2 responses. OBJECTIVES To assess the effectiveness of cloth and medical masks for preventing SARS-CoV-2 transmission in community settings. METHODS Two rapid reviews were conducted searching three electronic databases (PubMed, Embase, Cochrane Library) and two clinical trials registries on 30 and 31 March 2020. RESULTS We screened 821 records and assessed nine full-text articles for eligibility. One and seven RCTs were included for cloth and medical mask reviews, respectively. No SARS-CoV-2-specific RCTs and no cloth mask RCTs in community settings were identified. A single hospital-based RCT provided indirect evidence that, compared with medical masks, cloth masks probably increase clinical respiratory illnesses (relative risk (RR) 1.56; 95% confidence interval (CI) 0.98 - 2.49) and laboratory-confirmed respiratory virus infections (RR 1.54; 95% CI 0.88 - 2.70). Evidence for influenza-like illnesses (ILI) was uncertain (RR 13.00; 95% CI 1.69 - 100.03). Two RCTs provide low-certainty evidence that medical masks may make little to no difference to ILI infection risk versus no masks (RR 0.98; 95% CI 0.81 - 1.19) in the community setting. Five RCTs provide low-certainty evidence that medical masks may slightly reduce infection risk v. no masks (RR 0.81; 95% CI 0.55 - 1.20) in the household setting. CONCLUSIONS Direct evidence for cloth and medical mask efficacy and effectiveness in the community is limited. Decision-making for mask use may consider other factors such as feasibility and SARS-CoV-2 transmission dynamics; however, well-designed comparative effectiveness studies are required.