Your questions answered: Should I wear a mask if I've already had COVID?

This story idea came from audience members, like you, who got in touch with us. Send us your questions about COVID-19 and masking. We are listening: ask@cbc.ca

As Canadians look ahead to summer vacation plans with friends and family, there are still lingering questions about which safety precautions are necessary and which ones are overkill, now that public health restrictions have relaxed.

Many of you sent in questions after reading this article about how to navigate a mask-optional Canada. CBC News followed up, and got the answers you were looking for.

Do I need to wear a mask if I've had COVID? 

Several of you wanted to know whether wearing a mask was necessary if you've recently recovered from COVID. 

The answer to that question depends on a few factors. First off, if you are currently positive for COVID-19 or if you've been in close contact with someone who is, health authorities recommend you wear a mask to protect others.

But even if you've recovered from COVID and are no longer testing positive, wearing a mask in an indoor public setting could still be a good idea.

Raywat Deonandan, an epidemiologist and associate professor at the University of Ottawa, said masks serve several purposes: they protect others from you if you're infectious and they protect you from others who might be infectious. Plus, he adds, wearing a mask also signals to others that you care about their health.

If you recently caught COVID but are no longer testing positive, Deonandan said you're not likely to be an infectious threat to others, and you're not likely at risk of getting infected right away.

But he still recommends wearing a mask — both for social reasons and because there's a lot of uncertainty around how long immunity lasts.

With previous variants, Deonandan said immunity lasted about 90 days. With Omicron, he said people can get reinfected in about 60 days, and that's only an average.

"Some people will get reinfected much sooner, and some much later," he said. 

Complicating things further is the fact that access to the more sensitive polymerase chain reaction (PCR) testing is limited, leaving most people to rely on at-home rapid antigen tests (RATs) to evaluate if they're infectious.

"If you are PCR negative, there's a very low probability you are carrying infection. But if you test negative on a single RAT after a known infection, there is a real possibility that you are still infected, with questionable viral load," Deonandan said. 

That's why he recommends erring on the side of caution and wearing a mask.

People with hybrid immunity — those who are fully vaccinated and have recovered from COVID-19 — could still be at risk of catching the virus if there's enough of it circulating, Deonandan said.

"It's like wearing a water-resistant jacket in light rain — you will remain dry. But the same jacket will [leave] you soaking wet in a torrential downpour," he said. 

How well do masks work in general?

Some readers wrote in to ask for more information about how well masks work.

In February, the U.S. Centers for Disease Control and Prevention released a report, which you can read here, which found the consistent use of a high-quality face mask or respirator in indoor public settings was associated with lower odds of testing positive for COVID-19.

The study followed California residents who received a test result for COVID-19 between February and December 2021.

According to that research, N95 or KN95 respirators were found to be most likely to reduce the chance of testing positive, followed by surgical masks and finally cloth masks. 

Are cloth masks still effective?  

Cloth masks are "slightly better than nothing" according to Steve Rogak, an engineering professor at the University of British Columbia who studies the efficacy of different kinds of masks.

He said he personally prefers to opt for more effective masks, or to limit indoor time with vulnerable or infectious people.

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Deonandan explained that it all comes down to one question: if you're in a room with someone who has COVID-19, how long does it take to get infected? 

"[It] depends on the variant, distance, and vaccination status. But in general, if one or both people are wearing respirator masks, that time is measured in hours. If one or both are wearing cloth masks, it's measured in minutes."

What about Canadian-made alternatives? 

Some of you asked about alternatives to N95s and KN95 masks, such as the Canadian-made CAN95 mask.

The Canadian-made mask manufactured in Burnaby, BC is authorized by Health Canada. Rogak said CAN95 masks should offer approximately the same level of protection as N95 and KN95, as long as they fit well.

Is it necessary to wear protective eyewear?

While it's possible to be infected through the mucous membranes of the eye, protective eyewear might be unnecessary. 

"If you want as close to 100 per cent protection as possible, then eye protection is worthwhile. But from a population health perspective, if we're looking at strategies to slow down transmission at the population level, I'm not sure eyewear offers any substantial reduction in overall risk," Deonandan said. 

Do I need to wear a mask while exercising outdoors? 

One reader who enjoys running asked if a mask was necessary while participating in outdoor track meets. 

Rogak said in that context, the risk of getting COVID outdoors would likely be negligible. But on the other hand, spectators gathered in a crowded area to watch athletes compete would have a more elevated risk of catching the virus — even outdoors. He said in that situation, vulnerable people might want to don a mask.

Can the virus spread when I touch my mask?

Some of you wanted to know if you can spread the virus by touching it when you take it off, or by hanging it up in your car. 

The Public Health Agency of Canada advises people to wash their hands or use hand sanitizer before and after touching or removing a mask. 

While it is theoretically possible for the virus to spread through surfaces, Deonandan said "there is scant evidence that that has been an appreciable avenue for transmission anywhere in the world."