The fourth wave of COVID-19 that public health experts have been warning about for months has arrived.
“The latest national surveillance data indicate that a fourth wave is underway in Canada and that cases are plotting along a strong resurgence trajectory,” said Dr. Theresa Tam, Canada’s chief public health officer, at a press conference Thursday.
However, experts say this wave might look a little different than previous ones. Here’s what could happen.
It’s already here
If the word of the chief public health officer of Canada isn’t enough, data from PHAC shows a clear rise in cases.
“We are seeing an increase in numbers, and it’s mostly amongst the unvaccinated,” said Dr. Cora Constantinescu, a pediatric infectious diseases specialist with the University of Calgary.
“Our hospitalizations are going up, at least in Alberta. ICU stays are going up as part of the numbers from our chief medical officer of health, and R0, which is how many people one person infects, is going up, which is all a sign of an outbreak or a wave.”
Delta will drive it
According to preliminary data from the Public Health Agency of Canada, the Delta variant has essentially taken over in Canada. It was only about eight per cent of cases during the week of May 9, 2021.
By July 11, it was 78 per cent — though the data remains incomplete, so this number could change.
However, public health experts have no doubt that Delta is driving the fourth wave.
“The Delta variant is a very highly contagious variant with a very high R0,” said Craig Janes, director of the school of public health sciences at the University of Waterloo.
“So it just means that we’re going to see probably this doubling (of case numbers) fairly quickly. With each week you’re going to see increasing cases.”
“Although we’re heading into the fourth wave driven by the Delta variant, the good news is that millions of Canadians have rolled up their sleeves to help build a strong wall of vaccination production,” Tam said Thursday.
The unvaccinated are most at risk
Experts agree that people who aren’t vaccinated — including children under 12 who are too young to be eligible for the shot — are most at risk in this wave of the pandemic.
“They call it the ‘pandemic of the unvaccinated,’” Dr. Anna Banerji, an infectious diseases specialist with the University of Toronto, told Global News earlier in the week.
“The vast majority of people that will get COVID will be the unvaccinated people. So, adults who continue to be unvaccinated or under-vaccinated and children under the age of 12 that are not eligible for vaccination right now.”
With the combination of the Delta variant affecting children in a way that original strains of COVID-19 didn’t and lower vaccination rates in younger people, “We’re going to see a lot of younger people getting sick and winding up in the hospital,” Janes said.
Ontario recently started releasing data on hospitalization numbers that include vaccine status.
At first look, unvaccinated people represent 81 per cent of non-ICU hospital patients with COVID-19 in the province. Partially-vaccinated people represent 8 per cent and fully-vaccinated people are 11 per cent.
However, it’s worth remembering that most Ontarians — 64 per cent — are fully vaccinated right now. So, taking that into account, the unvaccinated are 15 times more likely to be in hospital with COVID-19 than people who are fully vaccinated: a rate of 1.5 per 100,000 compared to 0.1 per 100,000.
Alberta is showing similar figures. According to the government website, 92 per cent of hospitalized cases since January occurred in unvaccinated people, or in people who got sick less than two weeks after their first dose. Unvaccinated people account for the vast majority of people with COVID-19 currently in Alberta hospitals and ICUs.
“I think the picture has changed for adults because of vaccination and because of our fantastic rate of vaccination in Canada,” Constantinescu said.
“I think this has changed for adults to a huge extent. We’re not seeing the same hospitalization and death, but for children, it’s the same. So because our kids are unvaccinated, the only way our children are safe is if the numbers in our society are low.”
Hospitalizations might not match case numbers
Because of the high vaccination rate, epidemiologists suggest that we might not see hospitalizations stay as closely linked to case numbers as they were in the past.
“You’ll see cases going up, but without the corresponding increase in hospitalization,” Janes said. He thinks that this is because older people, who are most likely to end up in the hospital, tend also to be the most-vaccinated group.
So even if younger people get infected, they likely won’t be going to hospital in the same numbers as older people were earlier in the pandemic, he thinks.
We might be seeing this now in the U.K., he said, where case numbers are rising but hospitalization isn’t at the same rate.
Public health measures need to maintained to control it
How do we stop the fourth wave? “Get vaccinated!” said Constantinescu.
“If you haven’t had the first dose, have the first dose,” she said, but, “the second dose is much more magical.”
Because children can’t be vaccinated, it’s especially important that those around them are, she said.
Aside from vaccination, she thinks that it’s a good idea to continue to wear masks indoors. “There’s no doubt in my mind that when indoor masking went down, COVID came up again,” she said.
Finally, if you’re feeling sick, even with just a sore throat, you should stay home, she said.
Over time, Janes said, “This pandemic may end in terms of waves of hospitalizations and some serious illness, but it’s not going to go away. It’ll just simply become endemic.”
Public health practitioners are most concerned about serious illness, he explained. “It’s really the spikes in hospitalization. I think when those level off, we don’t see those anymore, that’s when I think we can feel we can be somewhat confident that the pandemic is over.”