VANCOUVER -- B.C.'s latest COVID-19 numbers show a younger demographic is making up the majority of new virus cases and while some in that age group have milder symptoms, new research suggests they could suffer serious long-term health effects from the virus.

Last week, B.C.'s top doctor revealed new modelling data on the virus. Those latest figures showed that while people in their 20s make up 13 per cent of the province's population, they make up 17 per cent of all cases identified since the start of the pandemic.  

CTV Morning Live spoke with family physician Dr. Melissa Lem on Monday to hear more about the lasting symptoms younger people could face. 

The following is part of a five-minute interview and has been edited for length and clarity. Watch the full interview above.

Jason Pires: There have been studies showing younger people can still suffer long-term effects of COVID-19. What are those?

Dr. Melissa Lem: Even though adults under 40 are at lower risk of dying from COVID-19, we're now seeing, as case numbers shift more towards this group, that they can develop serious, long-lasting symptoms. 

We have to keep in mind that even though 80 per cent of people get mild cases, one-in-five people do experience more serious effects that can last for months or forever, including weakness, chronic fatigue and brain fog, lung scarring, shortness of breath, loss of smell and taste, blood clots and strokes that can lead to permanent disability. 

There's also no guarantee that once you'll get it, you'll be immune. Some people have had multiple positive tests over a period of months with worsening symptoms … this may not be a lottery that young people want to risk playing. 

Keri Adams: Can you tell us about the recent study that found that teens who vape have a substantially higher risk of getting COVID-19?

Lem: About a week ago, a study from Stanford University showed that teachers and young adults who vape or smoke were seven times more likely to catch COVID-19 than those who don't. Again it shows that being young in this case, is not necessarily protective. 

Now there are a few possible reasons for this higher rate, including that smokers tend to touch their mouth and their faces more, and that cigarette smoke and vaping chemicals can cause lung damage and weaken your immune system. 

So if you vape or smoke, now is an especially good time to think about cutting back or quitting … and you should definitely avoid sharing cigarettes or vaping equipment with anyone else.

Pires: What are the higher risk activities where younger people seem to be catching this virus?

Lem: The factors that seem to increase the risk of catching COVID-19 the most are large groups of people, crowded together, shouting or singing indoors. All of these increase your risk of coming into contact with people with COVID-19 and their droplets. 

This makes indoor house parties and going to bars indoors two of the highest risk activities and sure enough that's where we've seen a lot of transmission in B.C. lately. 

That said, I think we have to do a better job at messaging overall. Instead of saying, "Just say no to parties," we should be emphasizing the fun things we can still do in small groups, like going for a hike or walk or enjoying a drink on an outdoor patio.

Watch the full interview above.