The second wave is coming. Here's what public health experts say we should expect

We asked dozens of physicians, epidemiologists and public health experts what to expect from a second wave of COVID-19 infections. Most said the severity of a second wave will depend on what infection-control measures governments put in place and whether or not people adhere to public health guidelines.

Doctors, epidemiologists and others surveyed by CBC outline what to expect in 2nd wave of COVID-19 infections

Some experts say a second wave of COVID-19 infections is inevitable, based on the history of similar infectious diseases, such as SARS, caused by a virus that is genetically related to the coronavirus, which causes COVID-19. (Graham Hughes/The Canadian Press)

For many health specialists in Montreal, a second wave of COVID-19 infections isn't a matter of if but when — and how bad it will be.

And some epidemiologists believe the second wave may already be underway. 

The good news is that many of these experts also say the severity and duration of that wave can be kept under control and that it is not a foregone conclusion that Quebec will again fare worse than the rest of the country.

Those observations are based on the answers that 170 medical doctors, epidemiologists, public health experts and medical researchers provided to CBC Montreal in an informal survey circulated earlier this month. 

Of the 170 who answered, two-thirds indicated that a second wave was "very likely." A further 24 per cent said it was "somewhat likely."

The concept of a second wave is contested and carries different meanings. It should be understood here at its most basic level: another sustained increase in infections.

Some experts believe a second wave is inevitable, based on the history of infectious diseases such as SARS, a respiratory illness caused by a virus that is genetically related to the coronavirus, which causes COVID-19. 

"It's useful to understand that a second wave is not a discrete thing that happens or doesn't," said Dr. Cédric Yansouni, an infectious-disease physician at the McGill University Health Centre in Montreal. "There haven't been any pandemics of respiratory diseases that had a single wave.

"You will always have ongoing transmission for some time. It can last for months and up to a two-year period."

Another reason a second wave is likely is that not enough people were infected in the first wave to generate sufficient levels of immunity in the population at large. 

"Second waves are expected for airborne transmitted viral infections for several reasons, the principal being the existence of a large population of unexposed [non-immune] hosts," said Tatiana Scorza, an immunologist at the Université du Québec à Montréal.

A study by Canada's COVID-19 Immunity Task Force, which did not include blood samples from Quebec, estimated that less than one per cent of Canadians have had the virus. The results of a separate study of Quebec blood samples are expected next month.

What will it look like?

There have been some indications that a second wave could already be underway in Quebec. 

After peaking in late April and early May, the rolling average of new cases in the province reached its lowest point in the final days of June.

But the average has climbed steadily since the start of the month, and now stands at more than 150 new cases per day. 

"If it starts increasing and not coming down over the next two weeks, I would say we'd be into a second wave," said Mark Goldberg, an environmental epidemiologist and professor in the department of medicine at McGill University.

The Quebec government says despite the increase in cases, the public-health situation remains under control. It points to the low number of deaths and hospitalizations. 

But Benoît Mâsse, a professor at the school of public health at Université de Montréal, cautioned that the increase in hospitalizations will likely come later.

He expects infections will increase for several more weeks. The danger, he said, is in September, when schools resume and the public begins to spend more time indoors, where the chances of infection are higher.

"We can expect a more substantial increase in infections with a rise in hospitalizations by the end of October, early November," Mâsse said in an email exchange.

WATCH: Quebec's health minister outlines preparations for second wave:

Quebec health minister speaks about the second wave

3 years ago
Duration 1:10
Health Minister Christian Dubé explains what the government is doing to prepare for a second wave of COVID-19 infections.

Other experts in Montreal are more reluctant to offer predictions. They stress that because the virus is new, there is a lack of data allowing them to anticipate infection patterns. 

Janusz Kaczorowski, a professor and research director in the department of emergency and family medicine at Université de Montréal, pointed out that many of his colleagues initially expected infections to decrease over the summer months, much like the flu, another virus thought to be transmitted by airborne droplets. 

"Look at what's happening now in the United States … I mean the numbers are going through the roof," Kaczorowski said. 

"It doesn't look like COVID is necessarily following the same pattern as the annual influenza. It is a different animal."

What should we do about it?

While experts maintain another round of infections is inevitable, they say its severity will depend on government policy and the willingness of the public to follow guidelines.

Not only do scientists know much more about COVID-19 than they did six months ago, but the public is better informed about hygiene measures and elected officials also have a wider range of policy tools at their disposal.

"I think everybody's learned a lot," said Dr. Brian White-Guay, a public health and family medicine specialist who teaches at Université de Montréal. 

"It's likely that things would be handled differently in a second-wave setting."

He suggested that health authorities, for example, now have a better understanding of which segments of the population are more vulnerable to COVID-19 and how best to protect them from the disease.

As part of the survey CBC Montreal and Radio-Canada circulated to health experts in early July, we asked an open-ended question about what the Quebec government should do when a second wave of the virus hits.

The most popular response? Make masks mandatory. 

Though the province implemented provincewide mask requirements in indoor public spaces as of July 18, the answers to our survey suggest the government was late in catching up with the scientific consensus. 

"It should have been done much earlier in the pandemic," said Dr. Eva Suarthana, a medical epidemiologist at Hôpital du Sacré-Coeur de Montréal.

Masks have been required in all indoor public spaces in Quebec since July 18. (Graham Hughes/The Canadian Press)

Another popular response was to stress protecting elderly Quebecers, especially those living in long-term care centres, where the vast majority of deaths occurred during the first wave.

Several experts said they were happy to see that provincial health authorities have already begun to implement tighter infection-control protocols and are training 10,000 new patient attendants for long-term care homes (CHSLDs).

But they also warned that delays in implementing these measures could come at a serious human cost.

"If we are not able to put in place proper measures to provide greater protection for [the] most vulnerable groups, there is reason to believe we would see a significant order of casualties, possibly up to the range of what we saw in the first wave," said White-Guay.


CBC collected 907 email addresses of health professionals from university and hospital websites. We sought out experts with research areas related to the pandemic, such as public health, epidemiology and emergency medicine. They were sent a questionnaire on July 7 and a reminder on July 10. 

Of the 180 responses, 10 were duplicates; 104 of the 907 emails sent bounced back with out-of-office replies or the email addresses were invalid.

This is the breakdown of professions that responded:

Infectious diseases, including epidemiology, immunology, virology: 41.
Emergency medicine: 23.
Public health: 20.
Family or general medicine: 17.
Epidemiology of non-infectious diseases: 6.
Biostatistics: 3.
Other medical specialization: 55.
Non-medical specialization: 5.

The questionnaire can be viewed here:

Mobile users: View the document
(Text KB)
CBC is not responsible for 3rd party content