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EID - The Practice of Wearing Surgical Masks during the COVID-19 Pandemic

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  • EID - The Practice of Wearing Surgical Masks during the COVID-19 Pandemic

    Volume 26, Number 8—August 2020


    The Practice of Wearing Surgical Masks during the COVID-19 Pandemic

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    Suggested citation for this article

    To the Editor: We read with interest the meta-analysis conducted by Xiao et al. (1) that found no significant reduction in influenza transmission with the use of surgical masks in the community, based on 10 randomized controlled trials. Nevertheless, mechanistic studies found that surgical masks could prevent transmission of human coronavirus and influenza virus infections if worn by infected persons (2). The authors pointed out the limitations of their study: small sample size and suboptimal adherence in the mask-wearer group (1). Recommendations on masks in the community vary across countries during the coronavirus disease (COVID-19) pandemic (3); studies have reported mixed results (2,4,5).

    Epidemiologic data may provide an alternative insight. As of April 3, 2020, Taiwan recorded 348 COVID-19 cases (1.46/100,000 population), of which 48 (13.8%) were local cases. Singapore recorded 1,114 cases (19.07/100,000 population), of which 572 (51.3%) were local cases. Taiwan and Singapore both employed stringent measures. Taiwan recommended the use of masks early in the pandemic. In contrast, Singapore did not recommend the use of masks until April 3 and initiated its Stay Home policy on April 7.

    Before the 2003 severe acute respiratory syndrome coronavirus epidemic in Taiwan, only persons with open tuberculosis wore masks in public. During the epidemic, wearing a mask in public was stigmatized. Thereafter, we educated the public to wear masks as a practice of respiratory hygiene. Although evidence is limited for their effectiveness in preventing transmission of severe acute respiratory syndrome coronavirus 2, either for source control or to reduce exposure, the wearing of masks by healthy persons may prevent potential asymptomatic or presymptomatic transmission (3). This marginal reduction in transmission may produce substantial results, particularly when it implemented early. Taiwan had the foresight to create a large stockpile of medical and surgical masks; other countries or regions might now consider doing so as part of future pandemic plans (3).

    Mr. Chiang is a medical student at National Taiwan University. His primary research interests are epidemiology and prevention of communicable diseases.


    Cho-Han Chiang, Cho-**** Chiang, Cho-Hsien Chiang, and Yee-Chun Chen

    Author affiliations: National Taiwan University College of Medicine, Taipei, Taiwan (Cho-Han Chiang, Y.-C. Chen); Fu-Jen Catholic University, Taipei (Cho-**** Chiang); Chung Shan Medical University, Taichung, Taiwan (Cho-Hsien Chiang); National Taiwan University Hospital, Taipei (Y.-C. Chen)

    1. Xiao J, Shiu EYC, Gao H, Wong JY, Fong MW, Ry u S, et al. Nonpharmaceutical measures for pandemic influenza in nonhealthcare settings—personal protective and environmental measures. Emerg Infect Dis. 2020;26:967–75. DOIExternal LinkPubMedExternal Link
    2. Leung NHL, Chu DKW, Shiu EYC, Chan KH, McDevit t JJ, Hau BJP, et al. Respiratory virus shedding in exhaled breath and efficacy of face masks. Nat Med. 2020 Apr 3 [Epub ahead of print]. DOIExternal Link
    3. Feng S, Shen C, Xia N, Song W, Fan M, Cowling BJ. Rational use of face masks in the COVID-19 pandemic. Lancet Resp Med. In press 2020. DOIExternal Link
    4. Ng K, Poon BH, Kiat Puar TH, Shan Quah JL, Loh WJ, Wong YJ, et al. COVID-19 and the risk to health care workers: a case report. Ann Intern Med. 2020 Mar 16 [Epub ahead of print]. DOIExternal LinkPubMedExternal Link
    5. Bae S, Kim MC, Kim JY, Cha HH, Lim JS, Jung J, et al. Effectiveness of surgical and cotton masks in blocking SARS–CoV-2: a controlled comparison in 4 patients. Ann Intern Med. 2020 Apr 6 [Epub ahead of print]. DOIExternal LinkPubMedExternal Link


    Suggested citation for this article: Chiang C-Ha, Chiang C-Hu, Chiang C-Hs, Chen Y-C. The practice of wearing surgical masks during the COVID-19 pandemic. Emerg Infect Dis. 2020 Aug [date cited].

    DOI: 10.3201/eid2608.201498

    Original Publication Date: 4/23/2020

  • #2

    The research team took three brands of commercially available disposable polypropylene masks that met international standards and washed them in eight different ways.

    They found that the disposable masks, which started off with 95 per cent efficacy, could be washed and dried 10 times and still work well, Everts said.

    The best way was simply washing in warm tap water for 10 seconds while gently massaging them, with no detergent, and then drying them to kill the bacteria, for reuse. This reduced the efficacy down to 80 per cent, which Everts said was still good. Two brands were still close to 90 per cent after 10 washes.

    Soaking masks in hot boiled water for five minutes had a similar effect.

    Disposable masks offered better protection than cloth masks. The best disposable masks would stop 95 per cent of all bugs, while only a few of the best commercially available cloth masks get above 90 per cent efficacy. Most were 70 per cent, Everts said.

    “Once people have made themselves at home, those will go anywhere from five to 20 per cent, so they’re not stopping many viruses at all.”

    Some people had sewn in three to four layers of material, which brought a cloth mask’s filtration efficacy up to about 30 or 40 per cent, he said, although it was then often harder to breathe.

    Filtration efficacy also reduced with cloth masks after a few washes, he said.
    ?The only security we have is our ability to adapt."


    • Emily
      Emily commented
      Editing a comment
      Thanks, Kiwi. We've been washing our surgical masks with no problem. The best ones are probably the ones China donated early in the pandemic. They were at a discount shop and the packages had an official stamp of quality in Chinese writing.