Wearing a face mask and keeping your distance from others can help to cut your relative risk of catching the novel coronavirus by 80 per cent or more, according to a new paper.
The study, published Monday in the Lancet medical journal, reviewed existing research on these common interventions with regard to SARS-CoV-2 and related coronaviruses and found that face masks, physical distancing and eye protection are all highly effective in stopping the virus, particularly in high-risk or medical settings.
While these interventions have been recommended by health officials for some time, this study provides specific evidence on their effectiveness.
Standing at least 1 metre away was found to reduce the likelihood of transmission from 12.8 per cent to 2.6 per cent, and standing even further away had an even stronger effect, the study found.
Masks also mattered, with N95 masks providing the greatest protection. Cloth masks with multiple layers protected better than single-layered masks. Similarly, eye protection, such as goggles or a plastic face shield, also made a difference.
“The risk for infection is highly dependent on distance to the individual infected and the type of face mask and eye protection worn,” the authors wrote in the study.
“From a policy and public health perspective, current policies of at least 1 m physical distancing seem to be strongly associated with a large protective effect, and distances of 2 m could be more effective. These data could also facilitate harmonisation of the definition of exposed (eg, within 2 m), which has implications for contact tracing.”
“All three of these measures combined are probably the best approach,” said Dr. Holger Schünemann, a professor of clinical epidemiology and medicine at McMaster University and co-author of the report.
But doing all of this won’t completely eliminate risk, he said. “None of that is sufficient. Although we didn’t look at it, hand hygiene and other types of hygiene measures obviously should not be left aside.”
“This study supports universal face mask use, because masks were equally effective in both health-care and community settings when adjusted for type of mask use,” wrote Raina MacIntyre, of the University of New South Wales and Quanyi Wang, of the Beijing Center for Disease Prevention and Control, in a linked commentary.
“Growing evidence for presymptomatic and asymptomatic transmission of SARS-CoV-2 further supports universal face mask use and distancing. In regions with a high incidence of COVID-19, universal face mask use combined with physical distancing could reduce the rate of infection (flatten the curve), even with modestly effective masks.”
Wearing a mask might not just stop you spreading the virus to others, as is commonly said, but could protect you too, Schünemann said. “We found some community studies, case studies, household studies that suggest that wearing a mask protects others but might also protect yourself,” he said.
The virus is thought to spread primarily by droplets, spread person-to-person when an infected individual speaks, coughs or sneezes, according to the U.S. Centers for Disease Control and Prevention. It may also spread if these droplets land on a surface, then a person touches that surface and then their own mouth or nose.
Currently, the Public Health Agency of Canada recommends that people avoid crowded areas and maintain a distance of two metres from others. In settings where it’s difficult to maintain physical distance, such as in a grocery store lineup, PHAC recommends wearing a non-medical mask.
Policies and the science behind them might change, Schünemann said, but right now, this review provides the “best available evidence” on how to prevent the virus from spreading.
Questions about COVID-19? Here are some things you need to know:
Symptoms can include fever, cough and difficulty breathing — very similar to a cold or flu. Some people can develop a more severe illness. People most at risk of this include older adults and people with severe chronic medical conditions like heart, lung or kidney disease. If you develop symptoms, contact public health authorities.
To prevent the virus from spreading, experts recommend frequent handwashing and coughing into your sleeve. They also recommend minimizing contact with others, staying home as much as possible and maintaining a distance of two metres from other people if you go out. In situations where you can’t keep a safe distance from others, public health officials recommend the use of a non-medical face mask or covering to prevent spreading the respiratory droplets that can carry the virus.
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