MONTREAL -- With entire countries on lockdown, borders closed, flights cancelled and 'social distancing' becoming the new norm, it seems a lot of people are wondering, what is it that makes COVID-19 so much more deadly than SARS or H1N1?

"For COVID-19, [transmissibility] is at a two or three. That means one person can give the virus to two or three other people," explains Dr. Chen Liang, an associate professor with McGill University's department of medicine. "For SARS, I believe it is one-point-something. It's quite low. So, this really makes COVID-19 a lot worse than SARS."

COVID-19 is just one of hundreds of strains related to severe acute respiratory syndrome-related coronavirus (SARSr-CoV).

Over the years, two strains of the virus have caused an outbreak in humans. The first occurred between 2002 and 2003, while the second is the pandemic of today.

"For COVID-19, we know very little about the virus. It's been only a few months and research takes time to really understand how this virus transmits," Liang explains. "For SARS, if you compare it to COVID-19, it had a much higher fatality rate. It's about 10 per cent; for COVID-19, it's now two per cent, but in some countries like Italy, it rises to around eight to 10 per cent."

He says the most dangerous part is that many people don't show symptoms of the virus.

"We're not created equal in that sense. We are all different and we all react differently to the same disease," Liang tells CTV News. "Young people appear to be more resistant to this virus and we don’t know why."


The reach of COVID-19 has been so widespread, it forced the World Health Organization (WHO) to declare it a pandemic – a disease or virus prevalent throughout an entire country, continent, or the world.

So far, across the world, there have been more than 188,000 cases of COVID-19 and more than 7,500 deaths.

In fact, the SARS-related coronavirus was actually one of several viruses identified by WHO in 2016 as a likely cause of future epidemics.

At the time, the organization had called for urgent research and development for diagnostic tests, vaccines and medicines.

This comes after the 2002-2003 outbreak, first reported in southern China, led to 8,098 confirmed cases and 774 deaths in 17 countries.

In Canada, the fourth region most affected following China, Hong Kong and Taiwan, there were 251 confirmed cases with 43 deaths.

There have been no reported cases of the original SARS since 2004.


Liang recalls when the H1N1 pandemic hit in 2009-2010, there was a lot of panic at the beginning – but nothing like today.

At the time, WHO confirmed 214 countries reported cases of H1N1/09, causing 18,036 confirmed deaths and 151,700 to 575,400 unconfirmed deaths by the summer of 2010.

"It turns out, in the end, that the swine flu pandemic was no worse than a seasonal flu," Liang notes. "Billions of people were infected. Around 200,000 people died in that one year."

He adds what quelled fears was that a vaccine quickly became available.

"We have the technology, all the resources, so if people work together, work very hard, it's possible to have a vaccine [for COVID-19], but again that takes time," he said, noting there is still no SARS vaccine. "You cannot skip a step. For safety reasons, it has to be effective and very safe."

On Aug. 10 2010, WHO declared the H1N1 influenza pandemic over, adding worldwide flu activity had returned to typical seasonal patterns.


Liang insists social distancing and self-isolation remains one of the best ways to prevent the spread of the virus.

"I believe it makes sense. You cannot just let the virus roam around and infect people and kill those who are vulnerable," he notes. "It’s the responsibility of the government and the public to do, so I strongly believe in that."

With a heavy price already being paid in terms of the economy, education and society as a whole, Liang admits it is, unfortunately, too early to say when the spread of the virus could die down.

"My hope – I think everybody also hopes – is that by summer, it will slow down and disappear and it will not come back," he said.