Canada's top public-health doctor is changing her advice about wearing masks as a way to prevent the spread of COVID-19.
Dr. Theresa Tam says wearing masks made of cloth and other alternative materials is a way for people who might have COVID-19 without realizing it to keep from spreading the illness.
She says people who wear masks must keep up other measures against COVID-19, including physical distancing and regular handwashing.
Tam stressed that medical masks still need to be preserved for front-line health workers.