Face Masks Could Reduce Coronavirus R Number and Prevent 2nd Wave, Scientists Say

Wearing face masks in public all the time could help epidemics of the COVID-19-causing coronavirus to die out and prevent future waves, according to a study.

The authors of the paper published in the journal Proceedings of the Royal Society A used existing data on how the coronavirus spreads, and the effectiveness of face masks and different lockdown scenarios to create computer models. A face mask was defined as a protective covering for the nose and mouth, designed to prevent the spread of germs.

The researchers considered factors including the proportion of the population that is likely to wear a face mask on any given day, and the effectiveness of different types of coverings, from clinical standard masks to those that are homemade.

The effect on the coronavirus' reproduction number (R)—or how many people a single person will pass a bug on to when they are infectious—appeared to be greatest when the majority of people wore what they described as "effective" face masks, such as N95 respirators used by healthcare professionals.

If the public wore effective face masks "all of the time," by complying with "normal facemask procedures in public," instead of just when they developed COVID-19 symptoms, the R number could be brought to below 1. This would lead to the epidemic "dying out," they authors wrote.

But even if people wore homemade face masks that were only 50 percent effective all the time, an R number of 2.2 could be brought down to below 1. The team also forecast that an R number of 4 could be brought to below 1 if 70 percent effective masks were worn all the time.

The authors wrote: "Under a wide range of plausible parameter conditions, facemask use by the public could significantly reduce the rate of COVID-19 spread, prevent further disease waves and allow less stringent lock-down regimes."

The findings were published days after the World Health Organization changed its advice or wearing face masks. After the UN agency said healthy individuals only need to wear a mask if taking care of a sick person, it now recommends people aged 60 or over and people of any age with underlying health conditions wear medical masks. The body said while there is "limited evidence" that non-medical, fabric masks are effective, members of the public should follow recommendations from their local authorities.

That advice was preceded by a paper published in the journal BMJ Global Health which stated wearing a face mask in the home could prevent the coronavirus from spreading between family members.

Richard Stutt, of Cambridge's Department of Plant Sciences who led the new study, said in a statement: "Our analyses support the immediate and universal adoption of face masks by the public.

"If widespread face mask use by the public is combined with physical distancing and some lockdown, it may offer an acceptable way of managing the pandemic and re-opening economic activity long before there is a working vaccine."

Co-author Renata Retkute, also of Cambridge's Department of Plant Sciences, said in a statement: "We have little to lose from the widespread adoption of face masks, but the gains could be significant."

Co-author Professor John Colvin of the University of Greenwich Natural Resources Institute said: "There is a common perception that wearing a facemask means you consider others a danger. In fact, by wearing a mask you are primarily protecting others from yourself.

"Cultural and even political issues may stop people wearing facemasks, so the message needs to be clear: 'my mask protects you, your mask protects me'."

There was a mixed response from experts not involved in the study to the findings. Dr Ellen Brooks Pollock, senior lecturer in veterinary public health and infectious disease modeling at the University of Bristol, said the likely impact of face masks is "much smaller" than predicted in the study.

She said the authors "optimistically assume that 100 percent of transmission events could be prevented with face masks.

"In reality, 15 percent of contacts and a third of all contact hours occur in the home, and therefore these transmission events would not be prevented with face mask use."

Trish Greenhalgh, professor of primary care health services at the University of Oxford, said in a written statement: "Overall, the model demonstrates that face coverings worn by a large percentage of the population (but not everyone) will be a crucially important measure in preventing a second and third wave of COVID-19 as we come out of lockdown. The findings are reassuring for those of us who sometimes don't follow perfect 'donning' and 'doffing' procedures: these are important for doctors and nurses when treating contagious patients, but the rest of us can relax because 'good enough' use of face coverings is likely to have the desired effect."

Keith Neal, emeritus professor of the epidemiology of infectious diseases at the University of Nottingham, said: "Clearly there is some face validity to the suggestions that the more people who wear masks the more impact this might have on the spread of COVID-19, but this is highly dependent on the effectiveness of the masks the public will use. The problem we have is there is no hard data on the effectiveness of the masks the public will use.

Neal also said like al modeling studies, the findings are "highly dependent on the assumptions made on these parameters. If any of the assumptions are significantly wrong this will affect the conclusion of the study."