New WHO study confirms face masks are effective in reducing COVID-19 spread
Health experts reviewed 172 studies to summarize findings in one clear document
Rafferty Baker · CBC News · Posted: Jun 11, 2020 3:00 AM PT | Last Updated: July 8
A Victoria, B.C., barber and client both wear masks during a haircut in May after provincial officials made them mandatory for hair salons to reopen. . (Michael McArthur/CBC)
Researchers who reviewed 172 studies about the effectiveness of masks, eye protection and physical distancing in decreasing the spread of COVID-19 confirm what many health officials have already been saying: They work.
The World Health Organization-funded study looked at research carried out in 16 countries on six continents in order to prepare clear guidance on the issue.
Dr. David Harris, a Vancouver infectious disease physician and one of the report's co-authors, said the study provides confidence that "the people who are making the recommendations are making them based on sound science."
"It's been confusing for a lot of people around mask use," said Harris. "From this review, we've found masking, or wearing any type of mask in the community does help ... mitigate that risk of transmission in the community, as well as in health care settings."
In British Columbia, early advice on wearing masks to prevent the spread of COVID-19 discouraged their use in the community, with the caution that they can give the person wearing a mask a false sense of security, and lead to extra face touching to adjust the mask.
In April, the message began to shift, and by late May masks were recommended in instances where physical distancing couldn't be maintained.
Advice from health officials about wearing face masks has changed during the pandemic. (Robert Short/CBC)
The new study confirms masks are effective both in health care and community settings.
Harris said there were initially mask shortages around the world which may have influenced the messages put out by health officials.
Harris said any type of mask is going to help reduce transmission of COVID-19 in the community.
"When I see somebody wearing a mask, I feel happy that they're wearing a mask because I know that they're — if they have it over their face and they cough or sneeze — they're protecting me," he said.
Harris said people who wear a mask improperly, leave it hanging around their chin or frequently adjust it, risk infecting themselves. But as long as they put it in front of their face when close to other people, they're reducing the risk of spreading the virus.
The WHO document that provides guidance based on the new study suggests ways to make more effective non-medical masks to be worn in the community.
It says non-elastic materials should be used to avoid increasing its pore size and multiple layers are important. Depending on the material, at least three layers should be used.
The WHO recommends a mask that fits snugly around the edges, with an inner layer made out of a fabric like cotton that absorbs moisture, and an outer layer made from polypropylene or polyester that repels moisture.