IN A NUTSHELL Author's NoteMask use in Vietnam evolved from a familiar daily habit into a critical public health intervention during the COVID-19 pandemic. Before the pandemic, researchers in Hanoi had already studied mask practices among healthcare workers, including one of the few randomized clinical trials comparing cloth masks and medical masks in hospital settings. Although this evidence received limited attention at first, it became highly relevant when COVID-19 raised urgent global questions about whether masks work, which masks should be used, and how they should be worn. The Vietnam studies showed that mask type, quality, fit, compliance, and correct use are essential. They also reinforced an important lesson for future pandemics: the right mask, used correctly in the right setting, can help reduce disease transmission and protect healthcare workers, patients, and communities
By Tham Chi Dung, MD., PhD.
Deputy Director
Research Institute for Health Sciences (RIHS), Hanoi city, Vietnam
Email: thamchidung@icloud.com
Link: (PDF) A cluster randomised trial of cloth masks compared with medical masks in healthcare workers
From Local Evidence to Global Lessons: Vietnam’s Mask Research and the COVID-19 Pandemic
Before COVID-19, masks were already familiar in Vietnam. People wore them on motorbikes, in crowded streets, in hospitals, and during seasonal respiratory outbreaks. However, before the pandemic, mask use was often understood more as protection against dust, pollution, or visible illness than as a central public health intervention.
Long before the world debated universal masking during COVID-19, researchers in Vietnam had already studied mask use among healthcare workers. These studies examined how masks were used in hospitals, what barriers healthcare workers faced, and how different types of masks performed in real clinical practice. This body of work later became highly relevant when the world urgently searched for evidence during the pandemic. [1–5]
One important study from Vietnam later became highly influential in global discussions on masks. The study, A cluster randomised trial of cloth masks compared with medical masks in healthcare workers, was conducted in 14 secondary and tertiary hospitals in Hanoi among 1,607 healthcare workers. It compared cloth masks, medical masks, and usual practice in high-risk hospital wards. The paper was published in BMJ Open in 2015 and was one of the very few randomized clinical trials directly comparing different types of masks in real healthcare settings. [1]
At the time of publication, the paper received limited attention outside infection prevention and occupational health communities. Its findings, however, were important. The study found that healthcare workers using cloth masks had higher rates of respiratory infection than those using medical masks. The authors concluded that cloth masks should not be recommended for healthcare workers in high-risk clinical settings, particularly when medical masks or respirators are available. Laboratory testing in the study also showed much higher particle penetration through cloth masks compared with medical masks. [1]
This trial was not an isolated effort. Earlier and related publications had already examined healthcare worker practices around face mask use, the use of cloth masks in Hanoi hospitals, and barriers to the use of facemasks and respirators among hospital-based healthcare workers. These studies helped build a practical evidence base on mask use before COVID-19 became a global crisis. [2–5]
When the first cases of a new coronavirus disease were reported in late 2019 and early 2020, the world entered a period of uncertainty. The disease was initially associated with a novel coronavirus and later officially linked to severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2. As COVID-19 spread globally, masks quickly became one of the most visible and debated tools for preventing transmission.
Many urgent questions emerged. Could masks prevent COVID-19? Should only sick people wear them, or should everyone wear them? Were cloth masks useful? Were medical masks better? When should N95 or equivalent respirators be used? How should masks be worn, removed, washed, or disposed of? Who should wear which type of mask in hospitals, in communities, and during outbreaks?
The urgency of these questions increased because SARS-CoV-2 could spread through respiratory droplets and aerosols, including from people with mild symptoms or no symptoms. Communities, healthcare workers, researchers, governments, and international agencies began searching for clinical evidence on mask effectiveness. They found that there were very few randomized trials on masks, and even fewer comparing mask types among healthcare workers. The Hanoi trial therefore became highly relevant because it offered rare clinical evidence from real hospital practice. [1]
During 2020 and 2021, this once relatively quiet paper became one of the most consulted studies on cloth masks and medical masks. It was cited in scientific reviews, public health debates, and policy discussions because it addressed a practical question that the world urgently needed to answer: not simply whether masks should be used, but which mask should be used, by whom, and in what setting.
The lesson from Vietnam’s mask study was not that masks do not work. Rather, it showed that mask quality, mask type, fit, compliance, and correct use matter greatly. In hospitals, healthcare workers need medical masks for routine care and respirators such as N95, FFP2, or equivalent masks for aerosol-generating procedures and high-risk infectious disease care. Cloth masks may have a role in the community when better masks are unavailable, but they should not replace medical masks or respirators for healthcare workers in high-risk clinical settings. [1,4,5]
The COVID-19 pandemic transformed masks from a simple personal habit into a global public health tool. In Vietnam, where mask wearing was already culturally acceptable, the practice became one of the visible symbols of collective responsibility. Masks helped protect individuals, families, patients, healthcare workers, and communities. They were most effective when combined with hand hygiene, ventilation, distancing, vaccination, testing, isolation, and clear risk communication.
The story of mask use in Vietnam therefore carries an important global message. A study conducted silently in Hanoi hospitals before the pandemic became a key source of evidence with million views and readings when the world urgently needed answers. It showed that masks are not all the same: the right mask, worn correctly, by the right person, in the right setting, can become a powerful tool to reduce disease transmission.
References
- MacIntyre CR, Seale H, Dung TC, Hien NT, Nga PT, Chughtai AA, Rahman B, Dwyer DE, Wang Q. A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open. 2015;5(4):e006577. doi:10.1136/bmjopen-2014-006577.
- Seale H, MacIntyre CR, McLaws ML, Maher L, Newall A, Kaur R, Nga PT, Nguyen TH, Dung TC, Dwyer DE. Health care worker practices around face mask use in hospitals in Hanoi, Vietnam. Int J Infect Dis. 2012;16 Suppl 1:e384. doi:10.1016/j.ijid.2012.05.503.
- Dung TC, Hien NT, Nga PT, Dinh PN, Seale H, MacIntyre CR, Maher L, Phuong N, Dwyer DE. Use of cloth masks among healthcare workers in hospitals in Hanoi. Vietnam Journal of Preventive Medicine. 2012;22(2):104-110.
- Chughtai AA, MacIntyre CR, Peng Y, Wang Q, Ashraf MO, Dung TC, et al. Practices around the use of masks and respirators among hospital health care workers in 3 diverse populations. Am J Infect Control. 2015;43(10):1116-1118. doi:10.1016/j.ajic.2015.06.006.
- Chughtai AA, Seale H, Dung TC, Hayen A, Rahman B, MacIntyre CR. Compliance with the use of medical and cloth masks among healthcare workers in Vietnam. Ann Occup Hyg. 2016;60(5):619-630. doi:10.1093/annhyg/mew008.
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