If you are young and think you are immune to COVID-19, some doctors would like you to pay attention to the following message:

"While COVID-19 is less likely to cause serious symptoms in younger people, in combination with substance use like vaping or smoking cigarettes or cannabis, it could pose a serious health threat," says a March 24 commentary written by Dr. Nicholas Chadi and Dr. Richard Bélanger of the Canadian Pediatric Society.

They are among the public health experts sounding the alarm about the possible connections between lung damage caused by smoking or vaping and increased vulnerability to the novel coronavirus.

The Canadian Pediatric Society commentary urges physicians and parents to make sure young people know:

Vaping and smoking — cigarettes or cannabis — weaken the lung's regular defences and affect cardiovascular health.

Based on observations of adults, these activities may put young people at increased risk of severe coronavirus infection.

Young people who smoke or vape may be more likely to develop complications from coronavirus like pneumonia or acute respiratory distress, which could result in hospitalization and/or treatment in an intensive care unit.

Stuart Stephen, left, and David Bergen, right, share a cigarette. They say they're not worried about physical distancing and the risk of COVID-19. (Jaison Empson/CBC News)

Outside the Polo Park Shopping Centre in Winnipeg, Stuart Stephen, 19, and David Bergen, 23, were huddled in the wind, sharing a smoke.

Asked if they are worried about sharing saliva, Stephen said "No."

"Not with him. We don't have coronavirus. I don't, he doesn't. Just a friendly smoke," he said, handing the cigarette to his friend.

Both of them say they have been smoking and vaping for years, but they don't seem concerned about the potential damage to their lungs and whether that makes them more at-risk for COVID-19.

"Coronavirus is more common in older people than younger, statistics have shown, so I'm not too worried about it," Stephen said.

Changing attitudes

That attitude is common, and is precisely the problem, said David Hammond, a professor in the School of Public Health at the University of Waterloo.

"It's part of this idea that young people have that they're bulletproof, that these things are for older people. Well, this is about changing that attitude, and doing it very quickly," he said.

There is evidence that smoking not only leads to respiratory diseases and chronic lung conditions, but also suppresses and harms the immune system, "so that when people do get sick, they have a harder time fighting it," Hammond said.

David Hammond of the University of Waterloo says young people need to realize they're not invincible when it comes to COVID-19. (Craig Chivers/CBC)

He points to some early research from China on the impact of COVID-19. One study that was published online in the Chinese Medical Journal involved 78 patients with COVID-19 and found those with a history of smoking were 14 times more likely to develop pneumonia.

Another study found men were slightly more likely than women to be hospitalized for coronavirus infection, which scientists say could be connected to the fact that Chinese men are also more likely to be smokers.

There is less research on the effects of vaping and risk of viral infection, but Hammond said people who vape regularly are exposing their respiratory tracts to different toxicants.

"We expect it to be much less than smoking, but it is possible that it still increases susceptibility in terms of the severity of experiencing COVID-19," he said.

WATCH | Sounding the alarm about smoking and vaping and COVID-19:

There's a growing body of research linking vaping, smoking cigarettes and cannabis to an increased risk of COVID-19 infection, serious illness, and death rates. 2:07

There's another concern. Vaping and smoking are often social activities, which is particularly problematic at a time when people are being implored to practise physical distancing to stop the spread of COVID-19.

"You do not want to be sharing anything that goes into other people's mouths. And we know that's very common for e-cigarettes and vape devices. And again, it's young people that are most likely to do that," Hammond said.

'Gonna try to quit'

As she left a Winnipeg vape shop, shopping bag in hand, Brandi Bourgeois said she's trying to wean herself off a lifelong smoking addiction by taking up e-cigarettes.

She's been in self-isolation with her family, but came into the city to do some grocery shopping and stock up on vape juice.

She is concerned that smoking and vaping could make her more vulnerable to COVID-19.

"I'm scared of course.... Gonna try to quit for sure," she said.

That's exactly what Neil Johnston wants to hear. He's a registered respiratory therapist and now head of the Manitoba Lung Association.

Johnston has noticed more people calling the association asking questions about lung disease and the coronavirus, and seeking advice on how to quit smoking. He points them to information on the association's website.

"It's one of those rough situations where it may be the best time to quit, but because smoking is a coping mechanism for dealing with stress, it might also be the worst time to quit," he said.

Neil Johnston of the Manitoba Lung Association wants public health officials to send an urgent message to young people: Stop smoking and vaping. (Jaison Empson/CBC News)

Having said that, if he could send one message to smokers and vapers, it's this: "Our lungs are made to breathe clean air. That's how they're designed. That's how they function best. … Don't smoke and don't vape. Keep your lung doors closed."

Johnston senses an increased interest in cessation programs, and he would like to see public health authorities making that a priority during this pandemic.

That idea was echoed in a March 20 article in the British Medical Journal, written by a trio of researchers that included an infectious disease scholar and two smoking-cessation researchers.

"It is likely," they wrote, "that the current concern about the COVID-19 epidemic provides a "teachable moment" in which smokers may be uniquely receptive to stop smoking advice."