Is my mask reusable if I leave it out? Your COVID-19 questions answered

We're answering your questions about the pandemic. Send yours to, and we’ll publish a selection of answers every weekday online, and also put some questions to the experts during The National and on CBC News Network.

From reusing masks to possible drug treatments, here's what you’re asking us today

Some viewers wonder if it's safe to reuse a mask that has been left out for a week. (Andrew Kelly/Reuters)

The information in this article was current at the time of publishing, but guidelines and advice can change quickly. Check with your local public health unit for the most-current guidance, and find the latest COVID-19 news on our website.

We're answering your questions about the pandemic. Send yours to, and we'll publish a selection of answers every weekday online, and also put some questions to the experts during The National and on CBC News Network. 

So far we've received more than 20,000 emails from across the country. As always, your questions have surprised us, stumped us and got us thinking.

Can I leave my mask out for a week until the virus dies and then reuse it?

This is a great question from Bradley N. We're not sure what sort of mask Bradley owns, but it's better to clean it than leave it out. Here's why: 

We know the coronavirus can persist on different surfaces for varying amounts of time, including masks. But when the virus has completely disappeared from a mask is hard to specify, especially if you're not applying any other decontamination measures. 

"It will depend on the mask material and conditions where it is sitting," said Dr. Anand Kumar, a critical care physician at Winnipeg's Health Sciences Centre with a background in infectious diseases. 

For a virus to go from being present to completely gone is a continuous process, he explains. It decreases over time but it's hard to verify when a mask is virus-free. 

"Leaving a mask out for a week will definitely decrease the viral load and the risk of getting infection from the mask. Will it protect you 100 per cent? We don't know," said Kumar.

That's because doctors aren't sure how much of the virus is needed for it to be potentially infectious — which means if some remnants linger on the mask, it could be harmful. 

If you are using a cloth mask, Health Canada recommends washing it on a hot cycle and drying thoroughly. You can read more of their guidance here

Some hospitals are using autoclaves to sterilize masks, including Kumar and his team. 

Should grocery store and pharmacy workers get priority testing?

Jeff in Vancouver is one of many who want to know whether grocery store and pharmacy workers should receive priority testing, like front-line health-care employees.

Infectious disease specialist Dr. Isaac Bogoch says yes.

Those who are "in touch with a large number of people every day" should be included in diagnostic testing, as well as "some form of surveillance" to ensure they are negative, he says. 

In fact, Bogoch says the threshold for testing should be much lower and says anyone who has compatible symptoms to COVID-19 should be tested.

WATCH | Who should get priority testing?

Should grocery store and pharmacy workers get priority testing as well?

1 year ago
Jeff E. from Vancouver is wondering if grocery store and pharmacy workers should be categorized in the high risk population and receive more frequent testing. 0:27

So why aren't we doing it? The problem for many provinces has been capacity.

Each province has been setting its own criteria for who gets tested, and it changes daily. For example, Alberta has begun testing more broadly, whereas Ontario and Quebec are focusing more on health-care workers, long-term care facilities and those with severe cases. 

Bogoch adds that expanding and sustaining testing is necessary to ensure a second wave of COVID-19 doesn't get out of hand. 

"Rapid access to diagnostic testing for the general population is going to be crucial," he said, adding that surveillance in the general community will be just as necessary.

Could a drug used to treat Ebola help COVID-19 patients?

We've received a number of questions about remdesivir, including an email from F. Knafo, who wants to know if this antiviral medication is being used in Canada?

No. There are currently no approved treatments or vaccines for the coronavirus. However, researchers suggest the drug, which was designed to treat Ebola, showed promising results against COVID-19 in one clinical trial. 

Leaked partial results from that trial suggest that out of 113 severely ill patients, most recovered and were sent home in a week; and two died. However, the data has not been peer-reviewed or published, so from a research perspective, experts say the findings are problematic. 

"Without a control group, it's really, really difficult to tell whether you're just picking the right patients who are doing better [or] whether this is something that would've happened anyway," said Dr. Ivan Oranski, who keeps tabs on the quality of scientific studies as the editorial vice president of Medscape.

"So it's good that these data are getting out there, but I think it's really premature."

WATCH | CBC's Vik Adhopia reports on remdesivir: 

Drug designed for Ebola a potential treatment for COVID-19

1 year ago
Researchers say Remdesivir, a drug designed to treat Ebola, is showing promising results against COVID-19 but warn it’s too soon to say. 1:57

Should long-term care residents be moved to hospitals once they test positive?  

Many including R. Chan are wondering whether long-term care residents who test positive should be automatically transferred to hospital. 

Patients with mild cases of COVID-19 can be treated in long-term care, as long as there is adequate staff, according to Dr. Kenneth Rockwood, a professor of geriatric medicine and a geriatrician at Halifax's Queen Elizabeth II Health Sciences Centre.

"The next stage of COVID-19 disease is severe illness," because patients often need oxygen, said Rockwood. But "this too can be done in long-term care," if the facility can cope. 

Adrian Wagg, division director of geriatric medicine at the University of Alberta, agrees that long-term care residents often do not fare well in hospital environments, especially if they are cognitively frail. 

However, some provinces including Ontario have recently revised their guidelines on treating outbreaks in long-term care homes. Now residents who develop a severe COVID-19 must be transferred to hospital by ambulance.

Has the virus mutated significantly? 

All viruses naturally evolve by gathering mutations, which simply means there are changes in its genetics.

The coronavirus "has mutated a little bit," says Bogoch, "but that just helps us understand where the virus is and how long it's been there."

Scientific sleuths look at changes in the genetic sequence of a virus to determine things like how long it has been in one place compared to another. 

"We often have this perception that mutation means that something is going to get stronger or more viral or more dangerous — that's not the case," says Bogoch. "In fact, most mutations do nothing."

Monday we answered questions about mattress contamination to street spraying.

Keep your questions coming by emailing us at


Ania Bessonov is a journalist with CBC Toronto and Ask CBC News.

With files from Michelle Song and Saman Malik

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