HKUST Co-led Study Suggests Universal Face Mask Wearing is Urgent Against Second Wave of COVID-19 Outbreak as Social Distancing Lifts


As governments worldwide are planning to gradually ease lockdown or social distancing measures after months of life disruptions due to COVID-19, an interdisciplinary study co-convened by a Hong Kong University of Science and Technology (HKUST) computer scientist has recently found that universal face mask wearing is an urgent non-pharmaceutical intervention to suppress the spread or second waves of the disease before effective vaccines or treatments are available.

The team, co-convened by De Kai, Professor of Computer Science and Engineering, presented two new theoretical models to predict the impact of face mask wearing over time.  The first extends the standard epidemiological SEIR model1 to predict the effects of mass face mask wearing. The second introduces an AI inspired agent-based model, which explicitly simulates infections occurring as a result of contact between individuals moving in physical space.  The team also took into account the varying degrees of mask effectiveness and found that the effects hold even with inexpensive, widely available non-medical face masks or homemade masks with only 70% effectiveness – an important factor in regions where medical-grade masks must be reserved for health workers.

The team’s simulation results show that if the vast majority (80%-90%) of the general public adopt masking on about day 50 after an outbreak, before lockdown measures are lifted, the number of new COVID-19 infections could be slowed significantly and help avoid a second wave of outbreak.  However, if face masking is not adopted nearly universally by the general public (for example if only half the population adopt masks) or if universal masking is delayed (for example to day 75), then significant slowing of the virus spread becomes unlikely.

The modeling results were validated and compared against empirical data from regions that have so far best managed their COVID-19 outbreaks such as Hong Kong, and Taiwan, where putting on face mask in public is culturally acceptable or government policies advise people to do so.  The data comparison shows a near perfect correlation between early universal masking and successful suppression of daily COVID-19 case growth rates and/or the rates of reduction from peak daily case growth.  In contrast, regions that did not implement early adoption of universal masking have instead needed to maintain a strict societal lockdown, with the attendant huge economic and social costs.

The study – a collaborative effort among an artificial intelligence professor, economist, computational molecular biologist, medical doctor / PhD, and behavioural scientist from Hong Kong, France, Estonia, the UK, and Finland – provides fresh insights into the urgency of putting on face masks in addition to continued physical distancing, increased testing, and contact tracing.

“Locking down our noses and mouths is far preferable to locking down our full bodies inside our homes,” said De Kai. “The cost of masks, including educating populations how to properly make and wear masks, is negligible in comparison to the large economic and human costs of increased infection rates. 

To provide the public and policy makers with a feel of how mass wearing of face masks impacts the spread of COVID-19, an interactive visualization of the simulation can be found here. Further resources can be found here.

1 In a SEIR model, the population is divided into groups that represent different states with respect to disease progression of any individual: S stands for susceptible, E stands for exposed, I stands for infectious and R stands for recovered or deceased.

About The Hong Kong University of Science and Technology
The Hong Kong University of Science and Technology (HKUST) ( is a world-class research university that focuses on science, technology and business as well as humanities and social science.  HKUST offers an international campus, and a holistic and interdisciplinary pedagogy to nurture well-rounded graduates with global vision, a strong entrepreneurial spirit and innovative thinking.  HKUST attained the highest proportion of internationally excellent research work in the Research Assessment Exercise 2014 of Hong Kong’s University Grants Committee, and is ranked as the world’s best young university in Times Higher Education’s Young University Rankings 2019.  Its graduates were ranked 10th worldwide and top in Greater China in Global Employability University Survey 2019.

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De Kai, Professor of Computer Science and Engineering, demonstrates how the interactive visualization of the simulation works.
De Kai, Professor of Computer Science and Engineering, demonstrates how the interactive visualization of the simulation works.

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