Since the onset of the COVID-19 pandemic, face masks have become the accessory du jour. Because of the increased demand for masks and other types of personal protective equipment we are on the brink of a global shortage where we may not even have enough supplies for frontline health care workers.
Some savvy individuals have started making their own reusable cloth masks out of various fabrics such as cotton or scuba. Available in a variety of patterns, they’re stylish and cost-effective. But do they work?
People seem to think they do. I had to visit the Emergency Department recently and saw the majority of doctors and nurses wearing brightly coloured, simply designed reusable masks. They were made by a local dressmaker who was selling three masks for $1000 JMD. The purpose of buying three was to interchange the masks, ostensibly to minimize soiling. Still, members of staff wore these masks for hours, whether or not they were directly interacting with a coughing patient.
My gut instinct says they’re probably not as effective as a disposable medical mask, but what does the literature say?
The first thing I learnt is that there is limited research on the efficiency of reusable fabric masks. Cloth masks have been studied from as far back as 1905 and as recent as 2017, with ambiguous conclusions.
In 2013, this article in the Journal of Infection Control acknowledged the historical use of cloth masks in protecting healthcare workers from respiratory illnesses1, and highlighted the lack of evidence around the efficiency of cloth masks, calling for further research. They argued that in an outbreak developing countries would not be able to consistently afford disposable surgical masks and respirators, but policy guidelines made no reference to the use of cloth masks, possibly because there wasn’t enough evidence.
The authors go a step further and tease out recommendations to improve the efficiency of reusable cloth masks (higher thread count, more layers and muslin instead of gauze), but they point out that most of their evidence comes from studies conducted in labs with mannequins as opposed to actual healthcare settings.
A 2015 randomised trial of cloth masks compared to surgical masks in Vietnam compared the outcome of clinical respiratory illness, influenza like illness (ILI) and lab-confirmed viral illness between clusters wearing disposable surgical masks and reusable face masks2. They found that the rate of all infections was highest for persons wearing cloth masks, particularly the rate of ILI and lab-confirmed infection.
(This is the only randomized control trial of cloth masks. )
A 2017 study in the Journal of exposure science evaluated the efficiency of three types of cloth masks and one type of surgical mask commonly used in developing countries in reducing exposure to particulate matter3. The study compared the filtration efficiency of each mask to the gold standard – N95 respirators. They concluded that:
Compared with cloth masks, surgical masks are more effective in reducing particulate exposure
And finally, The Lancet recently published an article discussing the “Rational use of face masks in the COVID-19 pandemic”4. The authors compared the policies of eight different health authorities on the use of face masks. Notably, China was the only country that explicitly recommended cloth masks or ‘non-medical masks’, and the recommendation was for persons at ‘very low risk’ of infection (those who mostly stay at home or in well-ventilated areas).
One interesting observation is that none of the studies I found examined whether wearing cloth masks was harmful i.e. associated with increased risk of infection compared to no mask at all. Theoretical discussions suggest that wearing a mask without a medical indication could increase your risk of infection if the mask is used improperly or for long periods or if you develop a false sense of security and forego other preventative measures such as hand washing. But before the advent of mass produced disposable masks, cloth masks were our best protection against infection. Can they help us still?
There is a plethora of emerging research on all things related to COVID-19, an outbreak which has been described as the greatest clinical challenge of our generation. Now is the time to explore and evaluate cost-effective resources for health, especially as the pandemic threatens the health of the most vulnerable among us.
References
1 Chughtai AA, Seale H, MacIntyre CR. Use of cloth masks in the practice of infection control – evidence and policy gaps. Int J Infec Control 2013 9(3). doi:10.3396/IJIC.v9i3.020.13
2 MacIntyre CR, Seale H, Dung TC, et al. A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open 2015;5:e006577. doi: 10.1136/bmjopen-2014-006577
3 Shakya, K., Noyes, A., Kallin, R. et al. Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure. J Expo Sci Environ Epidemiol 27, 352–357 (2017). https://doi.org/10.1038/jes.2016.42
4 Feng, S., Shen, C., Xia, N., Song, W., Fan, M., & Cowling, B. J. (2020). Rational use of face masks in the COVID-19 pandemic. The Lancet Respiratory Medicine. doi: 10.1016/s2213-2600(20)30134-x
well read robin 