The Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia
College of Public Affairs and Community Solutions, Arizona State University, Tempe, Arizona, USA.
BMJ Open. 2020 Sep 28;10(9):e042045. doi: 10.1136/bmjopen-2020-042045.
In a previous randomised controlled trial (RCT) in hospital healthcare workers (HCWs), cloth masks resulted in a higher risk of respiratory infections compared with medical masks. This was the only published RCT of cloth masks at the time of the COVID-19 pandemic.
To do a post hoc analysis of unpublished data on mask washing and mask contamination from the original RCT to further understand poor performance of the two-layered cotton cloth mask used by HCWs in that RCT.
14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam.
A subgroup of 607 HCWs aged ≥18 years working full time in selected high-risk wards, who used a two-layered cloth mask and were part of a randomised controlled clinical trial comparing medical masks and cloth masks.
Washing method for cloth masks (self-washing or hospital laundry). A substudy of contamination of a sample of 15 cloth and medical masks was also conducted.
Infection rate over 4 weeks of follow up and viral contamination of masks tested by multiplex PCR.
Viral contamination with rhinovirus was identified on both used medical and cloth masks. Most HCW (77% of daily washing) self-washed their masks by hand. The risk of infection was more than double among HCW self-washing their masks compared with the hospital laundry (HR 2.04 (95% CI 1.03 to 4.00); p=0.04). There was no significant difference in infection between HCW who wore cloth masks washed in the hospital laundry compared with medical masks (p=0.5).
Using self-reported method of washing, we showed double the risk of infection with seasonal respiratory viruses if masks were self-washed by hand by HCWs. The majority of HCWs in the study reported hand-washing their mask themselves. This could explain the poor performance of two layered cloth masks, if the self-washing was inadequate. Cloth masks washed in the hospital laundry were as protective as medical masks. Both cloth and medical masks were contaminated, but only cloth masks were reused in the study, reiterating the importance of daily washing of reusable cloth masks using proper method. A well-washed cloth mask can be as protective as a medical mask.
ACTRN12610000887077.
在之前的一项针对医院医护人员（HCWs）的随机对照试验（RCT）中，与医用口罩相比，布口罩导致呼吸道感染的风险更高。这是 COVID-19 大流行期间唯一发表的关于布口罩的 RCT。
对原始 RCT 中关于口罩清洗和口罩污染的未发表数据进行事后分析，以进一步了解在该 RCT 中使用的双层棉质布口罩表现不佳的原因。
越南河内的 14 家二级/三级医院。
年龄≥18 岁的全职在选定高风险病房工作的 607 名 HCWs 为研究对象，他们使用了两层布口罩，是一项比较医用口罩和布口罩的随机对照临床试验的一部分。
布口罩的清洗方法（自行清洗或医院清洗）。还对 15 个布口罩和医用口罩的样本污染进行了子研究。
在 4 周的随访中，通过多重 PCR 检测到了鼻病毒的污染。在使用过的医用口罩和布口罩上都发现了鼻病毒的污染。大多数 HCW（77%每天清洗）都是手洗口罩。与医院洗衣相比，自行手洗口罩的 HCW 的感染风险高出两倍以上（HR 2.04（95%CI 1.03 至 4.00）；p=0.04）。与医用口罩相比，在医院洗衣店清洗的布口罩对感染没有显著差异（p=0.5）。
使用自我报告的清洗方法，我们发现如果 HCW 自行用手清洗口罩，感染季节性呼吸道病毒的风险会增加一倍。研究中的大多数 HCW 都报告说他们自己手洗口罩。如果自我清洗不充分，这可能解释了两层布口罩表现不佳的原因。在医院洗衣店清洗的布口罩与医用口罩一样具有保护作用。两种口罩都受到了污染，但在研究中仅重复使用了布口罩，再次强调了使用正确方法每天清洗可重复使用的布口罩的重要性。清洗良好的布口罩可以与医用口罩一样具有保护作用。
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