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Contamination and washing of cloth masks and risk of infection among hospital health workers in Vietnam: a post hoc analysis of a randomised controlled trial.
BMJ Open. 2020 09 28; 10(9):e042045.BO

Abstract

BACKGROUND

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.

OBJECTIVE

To do a post hoc analysis of unpublished data on mask washing and mask contamination from the original RCT to further understand poor performance of the two-layered cotton cloth mask used by HCWs in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.

SETTING

14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam.

PARTICIPANTS

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.

INTERVENTION

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.

OUTCOME MEASURE

Infection rate over 4 weeks of follow up and viral contamination of masks tested by multiplex PCR.

RESULTS

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).

CONCLUSIONS

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.

TRIAL RESGISTRATION NUMBER

ACTRN12610000887077.

Authors+Show Affiliations

The Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia rainam@protonmail.com. College of Public Affairs and Community Solutions, Arizona State University, Tempe, Arizona, USA.Ministry of Health, Vietnam, Hanoi, Viet Nam.School of Public Health and Community Medicine, University of New South Wales, Sydney, New South Wales, Australia.School of Public Health and Community Medicine, University of New South Wales, Sydney, New South Wales, Australia.School of Public Health and Community Medicine, University of New South Wales, Sydney, New South Wales, Australia.

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

32988954

Citation

MacIntyre, Chandini Raina, et al. "Contamination and Washing of Cloth Masks and Risk of Infection Among Hospital Health Workers in Vietnam: a Post Hoc Analysis of a Randomised Controlled Trial." BMJ Open, vol. 10, no. 9, 2020, pp. e042045.
MacIntyre CR, Dung TC, Chughtai AA, et al. Contamination and washing of cloth masks and risk of infection among hospital health workers in Vietnam: a post hoc analysis of a randomised controlled trial. BMJ Open. 2020;10(9):e042045.
MacIntyre, C. R., Dung, T. C., Chughtai, A. A., Seale, H., & Rahman, B. (2020). Contamination and washing of cloth masks and risk of infection among hospital health workers in Vietnam: a post hoc analysis of a randomised controlled trial. BMJ Open, 10(9), e042045. https://doi.org/10.1136/bmjopen-2020-042045
MacIntyre CR, et al. Contamination and Washing of Cloth Masks and Risk of Infection Among Hospital Health Workers in Vietnam: a Post Hoc Analysis of a Randomised Controlled Trial. BMJ Open. 2020 09 28;10(9):e042045. PubMed PMID: 32988954.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Contamination and washing of cloth masks and risk of infection among hospital health workers in Vietnam: a post hoc analysis of a randomised controlled trial. AU - MacIntyre,Chandini Raina, AU - Dung,Tham Chi, AU - Chughtai,Abrar Ahmad, AU - Seale,Holly, AU - Rahman,Bayzidur, Y1 - 2020/09/28/ PY - 2020/9/29/entrez PY - 2020/9/30/pubmed PY - 2020/10/21/medline KW - infection control KW - infectious diseases KW - respiratory infections SP - e042045 EP - e042045 JF - BMJ open JO - BMJ Open VL - 10 IS - 9 N2 - BACKGROUND: 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. OBJECTIVE: 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. SETTING: 14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam. PARTICIPANTS: 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. INTERVENTION: 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. OUTCOME MEASURE: Infection rate over 4 weeks of follow up and viral contamination of masks tested by multiplex PCR. RESULTS: 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). CONCLUSIONS: 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. TRIAL RESGISTRATION NUMBER: ACTRN12610000887077. SN - 2044-6055 UR - https://www.unboundmedicine.com/medline/citation/32988954/Contamination_and_washing_of_cloth_masks_and_risk_of_infection_among_hospital_health_workers_in_Vietnam:_a_post_hoc_analysis_of_a_randomised_controlled_trial_ L2 - https://bmjopen.bmj.com/lookup/pmidlookup?view=long&pmid=32988954 DB - PRIME DP - Unbound Medicine ER -