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Meta-Analysis
. 2021 Feb 22;11(2):e044364.
doi: 10.1136/bmjopen-2020-044364.

Downsides of face masks and possible mitigation strategies: a systematic review and meta-analysis

Mina Bakhit  1 , Natalia Krzyzaniak  2 , Anna Mae Scott  2 , Justin Clark  2 , Paul Glasziou  2 , Chris Del Mar  2
Affiliations
Meta-Analysis

Downsides of face masks and possible mitigation strategies: a systematic review and meta-analysis

Mina Bakhit et al. BMJ Open. .

Abstract

Objective: To identify, appraise and synthesise studies evaluating the downsides of wearing face masks in any setting. We also discuss potential strategies to mitigate these downsides.

Design: Systematic review and meta-analysis.

Data sources: PubMed, Embase, CENTRAL and EuropePMC were searched (inception-18 May 2020), and clinical registries were searched via CENTRAL. We also did a forward-backward citation search of the included studies.

Inclusion criteria: We included randomised controlled trials and observational studies comparing face mask use to any active intervention or to control.

Data extraction and analysis: Two author pairs independently screened articles for inclusion, extracted data and assessed the quality of included studies. The primary outcomes were compliance, discomforts, harms and adverse events of wearing face masks.

Results: We screened 5471 articles, including 37 (40 references); 11 were meta-analysed. For mask wear adherence, 47% (95% CI 25% to 68%, p<0.0001), more people wore face masks in the face mask group compared with control; adherence was significantly higher (26%, 95% CI 8% to 46%, p<0.01) in the surgical/medical mask group than in N95/P2 group. The largest number of studies reported on the discomfort and irritation outcome (20 studies); fewest reported on the misuse of masks, and none reported on mask contamination or risk compensation behaviour. Risk of bias was generally high for blinding of participants and personnel and low for attrition and reporting biases.

Conclusions: There are insufficient data to quantify all of the adverse effects that might reduce the acceptability, adherence and effectiveness of face masks. New research on face masks should assess and report the harms and downsides. Urgent research is also needed on methods and designs to mitigate the downsides of face mask wearing, particularly the assessment of possible alternatives.

Systematic review registration: Open Science Framework website https://osf.io/sa6kf/ (timestamp 20-05-2020).

Keywords: COVID-19; health policy; public health.

PubMed Disclaimer

Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
PRISMA flow diagram.
Figure 2
Figure 2
Risk of bias graph: review authors’ judgements about each risk of bias item presented as percentages across all included studies.
Figure 3
Figure 3
Comparison of adherence to face masks versus control.
Figure 4
Figure 4
Comparison of adherence to surgical/medical face masks vs N95/P2 masks.
See this image and copyright information in PMC

References

    1. Tellier R, Li Y, Cowling BJ, et al. . Recognition of aerosol transmission of infectious agents: a commentary. BMC Infect Dis 2019;19:101. 10.1186/s12879-019-3707-y - DOI - PMC - PubMed
    1. Bartoszko JJ, Farooqi MAM, Alhazzani W, et al. . Medical masks vs N95 respirators for preventing COVID-19 in healthcare workers: a systematic review and meta-analysis of randomized trials. Influenza Other Respir Viruses 2020;14:365–73. 10.1111/irv.12745 - DOI - PMC - PubMed
    1. Jefferson T, Jones M, Al Ansari LA. Physical interventions to interrupt or reduce the spread of respiratory viruses. Part 1 - Face masks, eye protection and person distancing: systematic review and meta-analysis. medRxiv 2020:2020.03.30.20047217.
    1. Offeddu V, Yung CF, Low MSF, et al. . Effectiveness of masks and respirators against respiratory infections in healthcare workers: a systematic review and meta-analysis. Clin Infect Dis 2017;65:1934–42. 10.1093/cid/cix681 - DOI - PMC - PubMed
    1. Chu DK, Akl EA, Duda S, et al. . Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020;395:1973–87. 10.1016/S0140-6736(20)31142-9 - DOI - PMC - PubMed

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