Nonmedical Masks in Public for Respiratory Pandemics: Droplet Retention by Two-Layer Textile Barrier Fully Protects Germ-free Mice from Bacteria in Droplets

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Abstract

Due to the shortage of masks during the pandemic, we recently demonstrated that household textiles are effective environmental droplet barriers (EDBs) with identical droplet retention potential as medical masks. To further promote the implementation of a universal community droplet reduction solution based on a synchronized encouragement/enforcement of mask utilization by the public based on widely available textiles (mask fabrication without the need for sewing machines), here we conducted a study using germ-free mice to determine to what extent textiles were effective in vivo . Using a bacterial-suspension spray simulation model of droplet ejection (mimicking a sneeze), we quantified the extent by which 100% cotton textile prevented the contamination of germ-free animals on the other side of the textile-barrier (simulating a properly worn mask). Of relevance, all mice protected with textiles remained germ-free after two sprays (inoculation dose: >600 bacterial droplet units per 56.75cm 2 ) compared to the contamination of mice not protected by a textile (0/12 vs 6/6, Fisher’s exact, p<0.0001). In a second phase of the experiment with 12 germ-free mice exposed again to 10-fold more droplets remained germ-free, while 100% of mice at 180cm became colonized with a single spray (0/8 vs 4/4, Fisher exact, p=0.002). Collectively, barriers protected all mice (even with low-density textiles, heavy vs. light fabric, T-test, p=0.0028) when using textile-EDB to cover the cages (0/20 vs 10/10, Fisher exact, p<0.0001). This study demonstrated, in vivo, that widely available household textiles are 100% effective at preventing contamination of the environment and the exposed animals by microbe-carrying droplets.

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  1. SciScore for 10.1101/2020.04.06.028688: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variableIn short, the reported experiment was conducted with eighteen 9-week-old germ-free (Swiss Webster) mice (males:females, 1:1), which were individually allocated to 18 germ-free cages, for repeated exposure to a cloud of micro-droplets.

    Table 2: Resources

    No key resources detected.


    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • No funding statement was detected.
    • No protocol registration statement was detected.

    About SciScore

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