A cluster randomised trial of cloth masks compared with medical masks in healthcare workers

Abstract

ObjectiveThe aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs). The null hypothesis is that there is no difference between medical masks and cloth masks.Setting14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam.Participants1607 hospital HCWs aged ≥18 years working full-time in selected high-risk wards.InterventionHospital wards were randomised to: medical masks, cloth masks or a control group (usual practice, which included mask wearing). Participants used the mask on every shift for 4 consecutive weeks.Main outcome measureClinical respiratory illness (CRI), influenza-like illness (ILI) and laboratory-confirmed respiratory virus infection.ResultsThe rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. An analysis by mask use showed ILI (RR=6.64, 95% CI 1.45 to 28.65) and laboratory-confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were significantly higher in the cloth masks group compared with the medical masks group. Penetration of cloth masks by particles was almost 97% and medical masks 44%.ConclusionsThis study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated.Trial registration numberAustralian New Zealand Clinical Trials Registry: ACTRN12610000887077.

Uptake and effectiveness of facemask against respiratory infections at mass gatherings: a systematic review

“…25 Similarly, in non-MG settings, effectiveness of facemask varied depending on the study endpoint. [42][43][44][45][46][47][48][49][50][51][52][72][73][74] Metaanalysis of RCTs involving facemask in non-MGs showed efficacy against ILI but not against laboratory-confirmed influenza. 14,15,75 This study is the first focussed systematic review that describes both the uptake and effectiveness of facemasks against respiratory infections in MGs, and it compiles a data pool of 12710 participants originating from more than 50 countries.…”

“…For instance, the uptake of facemask among HCWs in several studies ranged from 56.6% to 84.3% (average 70.7%). [42][43][44][45] On the other hand, the uptake of facemask among ordinary population in diverse household and community settings ranged from 38% to 80.7% (average 55%). [46][47][48][49][50][51][52] This could be explained by several individual or organisational factors.…”

Australian Hajj pilgrims' infection control beliefs and practices: Insight with implications for public health approaches

“…Another unique finding to emerge from our study was that female pilgrims preferred to use a niqab (face veil) instead of a facemask because the niqab is more comfortable and breathable. This has potential public health importance, as a recently published randomized trial identified that cloth masks actually increase the risk of ILI [25].…”

Effectiveness of vaccination and wearing masks on seasonal influenza in Matsumoto City, Japan, in the 2014/2015 season: An observational study among all elementary schoolchildren

“…A randomized clinical trial found that medical staff members who used a mask correctly had a decrease in virus transmission (MacIntyre et al, 2015). Although less is known about the efficacy of wearing a mask in community settings, wearing a mask showed efficacy in young adults (Aiello et al, 2010b, Aiello et al, 2012).…”