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

Abstract

BackgroundIn 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was the only published RCT of cloth masks at the time of the COVID-19 pandemic.ObjectiveTo do a post hoc analysis of unpublished data on mask washing and mask contamination from the original RCT to further understand poor performance of the two-layered cotton cloth mask used by HCWs in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.Setting14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam.ParticipantsA 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.InterventionWashing 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 measureInfection rate over 4 weeks of follow up and viral contamination of masks tested by multiplex PCR.ResultsViral 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).ConclusionsUsing 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 numberACTRN12610000887077.

A Cross-Sectional Study of Knowledge, Attitude, and Practice Towards Face Mask Use Amid the COVID-19 Pandemic Amongst University Students in Vietnam

“…There were still some participants (6.8%) who washed their masks after some days of use but less than a week or after every week of use. It is documented that a well-washed cloth mask can be as protective as a medical mask [ 25 ]. This makes proper washing of face mask a key requirement in ensuring the effectiveness of face mask [ 24 , 25 ].…”

“…It is documented that a well-washed cloth mask can be as protective as a medical mask [ 25 ]. This makes proper washing of face mask a key requirement in ensuring the effectiveness of face mask [ 24 , 25 ]. It is suggested that cloth mask should be washed appropriately in hot water and soap everyday [ 24 , 25 ].…”

“…This makes proper washing of face mask a key requirement in ensuring the effectiveness of face mask [ 24 , 25 ]. It is suggested that cloth mask should be washed appropriately in hot water and soap everyday [ 24 , 25 ]. Although we did not document the methods of washing cloth masks, a number of our participants did not wash their cloth masks at least every day indicating the need to educate the community regarding the correct washing of cloth masks after use.…”

The Impact of Universal Mask Use on SARS-COV-2 in Victoria, Australia on the Epidemic Trajectory of COVID-19

“…Cloth masks made according to sound design principles, such as at least 3 layers, a water-resistant outer layer, good fit around the face may be as effective as a surgical mask (40). In addition, daily and adequate washing of cloth masks is required for effectiveness (41). Ensuring access to good quality cloth masks, avoiding low quality face coverings such as scarves or bandanas, and providing information on the best methods for making a high-quality mask will enhance protection.…”

Rúška počas pandémie COVID-19 – áno, ale aké?(„Diabol je v detailoch“)

“…Pri každodennom individuálnom praní (v 75 % pri ručnom praní) dvojvrstvových textilných rúšok bolo riziko nákazy dvojnásobne vyššie oproti jednorazovým chirurgickým rúškam. V prípade ich profesionálneho každodenného prania (60 -90 °C) boli oba typy rúšok porovnateľné (9).…”