Aggressive measures applauded by experts

The critical number in Quebec right now isn’t how many people have the new coronavirus, but how many other people they and perhaps others who are not yet showing symptoms will infect, experts in disease control say.

So while some people might think the Quebec government’s announcements this weekend banning visits to seniors’ residences, long-term care facilities and hospitals and ordering bars, gyms and other public places to close are overkill, the aggressive measures are being welcomed by scientists.

“There’ll be more cases, we have to be realistic,” said Hélène Carabin, a professor of epidemiology in the Université de Montréal’s faculty of veterinary medicine and at the university’s school of public health.

“It’s a global thing. It’s not going to go away.

“But we don’t want it to infect people too quickly so that the health system can absorb whatever comes its way.”

Based on places like China, older people are more likely to experience the most severe symptoms of COVID -19 and a higher proportion of older people than younger people die from it, she said.

Depriving seniors of visits from family “is not cool, it’s not fun, it’s not good at all for them,” Carabin said. “We need to find alternatives. Help them use Skype, take the phone or whatever. But physical contact? We don’t want to kill our loved ones.”

The number of confirmed cases of COVID-19 in Quebec climbed to 39 on Sunday.

It may sound low to some, but the figure that matters in disease control is known as the reproductive number, representing how many people will be infected by a person who is infected.

With the new coronavirus, the figure is estimated to be about two to three.

And a critical factor in the spread of any illness is what proportion of the population isn’t immune.

Because COVID-19 is a new virus with no vaccine to prevent it or antiviral to treat it yet, the answer is everyone.

“We have no immunity,” Anne Gatignol, a virologist and professor with Mcgill University’s department of medicine, said.

“And two to three is quite important because (the spread) is going to be exponential. If you don’t stop it right now while there’s still time, it’s going to be like in Italy.”

That’s why social distancing measures — such as closing bars and gyms — are critical for slowing the spread of COVID-19, Gatignol said.

“Some places can hold 500 people,” she said of bars and clubs. “So just imagine if one of them is contaminated. It will not be two or three persons infected. It will be 10, 20, 50. We don’t know ... And all these people will contaminate all of their families, older people, and so on.”

As a comparison, measles, which has a reproductive number of 10, is more contagious than COVID-19. However, most of the population is immune to measles because of vaccination.

David Buckeridge, a professor with Mcgill University’s school of population and global health, qualified the social distancing measures announced by Premier François Legault this weekend as “entirely appropriate and probably late, but hopefully not too late.”

The Quebec government has probably looked and learned from other countries battling COVID -19, he said.

“There’s a small set of countries that have really managed to contain the virus,” he said, referring to Taiwan, and to some extent South Korea and Singapore, where the number of cases has been kept relatively low and where death rates have been very low.

“And then we’re seeing other countries that have just failed on containment, either because they didn’t try or they didn’t have the resources,” Buckeridge said, offering Italy as an example.

“And what they’re seeing in Italy is a complete overwhelming of their health care system,” he said. “This is a developed country with an equivalent or in some situations superior health-care system to what we have in Canada. And they just can’t cope.”

The reproductive number for any illness is influenced by four elements, Université de Montréal’s Carabin said: the rate of contact between people, the probability of transmission upon contact, the size of the population and the duration of infectiousness.

No one can control the duration of infection with COVID-19 because an antiviral treatment is not yet available, she said. An antiviral is expected to come before a vaccine, she added.

Since you can’t control the duration of infectiousness or the population size, Carabin said, the only factors that can be influenced are behavioural: reducing the amount of contact between people and reducing the probability of transmission when there is contact by getting people to wash their hands with soap, cough into their elbows and disinfect surfaces.

Buckeridge said he expects measures to reduce social contact to prevent the spread of COVID-19 will have to go on beyond a couple of weeks.

“Not to be alarmist, but this is probably something we’re going to have to do for weeks to come,” he said. “It’s not a time to panic. The point is that people need to take this very seriously. And anything we can do to reduce the probability we’re going to transmit the virus from one person to another we should be doing. So that means, certainly for people who are more vulnerable to not even leave their house.”

Some places can hold 500 people ... So just imagine if one of them is contaminated. It will not be two or three persons infected. It will be 10, 20, 50.