Two and a half years into the COVID mess, yet another immunity-dodging viral variant is driving a seventh wave of infections — even though half the country’s population, more than 17 million people, were infected with Omicron between December and May, and despite more than 80 per cent of the population having received at least two doses of a vaccine.
“As much as all of us would love the pandemic to be over we are seeing changes in the virus that continue to make this extremely challenging,” said Dr. Fahad Razak, an internist at Toronto’s St. Michael’s Hospital and the new scientific director of Ontario’s COVID-19 science advisory table.
Hospitalizations are creeping up in Atlantic Canada, Quebec, Ontario, Alberta. Cases have tripled and hospitalization rates have doubled across parts of Europe in the past two weeks. California is being slammed by a “stunning” summer wave. Australians are being urged to work from home as COVID cases swamp hospitals. “The virus is running freely,” the World Health Organization recently warned.
Dr. Catherine Hankins doesn’t want to anthropomorphize SARS-CoV-2, assign it human emotions or behaviour. It doesn’t have a brain, though it sometimes behaves as if it does. But it is making the most of our hunger, and the pressure, socially and economically, “to get out and return to a fuller life,” she said. The more transmission, the more opportunity for the virus to mutate and lob new variants at us like hammer throws.
Two and a half years in, the world is discovering SARS-CoV-2 isn’t behaving with neat, predictable, winter-bound waves like the flu, but with multiple rollers that are coming faster, each new wave starting before the last one hasn’t quite finished with us. Instead of a lull period, peaks are occurring within months of each other.
“People were saying this will be like a seasonal respiratory virus. ‘We’ll have a great summer and in the fall it will come back.’ It’s not acting like that. It has these cyclical waves. We’re now in July!” said Hankins, co-chair of Canada’s COVID-19 immunity task force and a professor of public and population health at McGill University.
“I do think, at this stage, we have to resign ourselves to wave after wave.”
Surges are still happening when most people have been vaccinated, boosted, infected or some combination of all three. It might seem depressing. But our “immunity wall” is helping dampen how the human body responds to each successive variant, American cardiologist and scientist Eric Topol recently blogged.
Everything that we’re seeing suggests that herd immunity is just not possible
BA.5-driven hospitalizations are on the rise, but they’re still mercifully below those of previous waves, and there’s an uncoupling from ICU admissions and deaths, Topol said. In the United Kingdom, fewer than half of COVID-related hospital admissions are “primarily” for COVID. The virus is still evolving, and scientists are keeping close watch over the latest entrant of interest, formally known as BA.2.75, which has a “wealth” of new mutations beyond the multiple mutations that debuted in the first version of Omicron that surfaced late last year, and that ripped through global populations. The wily virus, Topol said, is evolving like a “Formula One race car lapping around the track with humans in the stands.”
Dr. Terrance Snutch, chair of the Canadian COVID-19 Genomics Network, doesn’t believe the virus is doing anything differently than it’s always done, “which is to be mutating at a certain rate in populations that are susceptible.” It’s not so much that it’s necessarily mutating faster — the mutation rate hasn’t changed much, if at all, said Snutch, a professor in the Michael Smith Laboratories at the University of British Columbia. “What is happening is you have this large population now that has some significant amount of immune response to the virus, either through previous infections or vaccinations and boosting, or a combination of both.”
Unlike early in the pandemic, when no one was immune, “the virus is mutating in populations that have a fair amount of resistance to earlier forms,” Snutch said. The mutations that are arising now are only advantageous to the virus if they can skirt our existing immune responses: infect people who have been vaccinated or previously infected, and replicate inside them.
“The virus is finding a new niche in humans — a niche in highly vaccinated, boosted and previously infected people,” Snutch said. “These are very specific mutations.”
On the plus side, there’s no evidence BA.4 and BA.5 cause more severe disease, though one study in hamsters suggested BA.5 has a propensity for lodging deeper in the lungs. Hospitalizations in Canada are increasing, “but again we’re not seeing a huge increase in requirement for ventilators or a significant increase in death,” Snutch said. “Knock on wood that continues.”
While antibodies that neutralize SARS-CoV-2 and prevent infection peter out, the body’s T-cells that provide longer-lasting memory protection against the virus don’t get as much cred as they should, scientists say. A study published in March found that a COVID infection or vaccination produces sustained levels of T cells capable of recognizing the SARS-Cov-2 spike protein that last more than a year. “Even though some parts of the immune response wane, we can now see that T cells recognizing the virus are quite stable over time,” senior author and University of Melbourne immunologist Dr. Jennifer Juno reported when the study was released. After 15 months of monitoring, “they were still roughly 10-fold higher than someone who had never been exposed to the spike protein through infection or vaccination.” It may explain why we’re not seeing as many severe infections.
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There’s no way of knowing, what next? SARS-CoV-2 is likely going to be around forever, and traditional herd immunity for COVID was a “crazy idea based upon assumptions only justified by wishful thinking, not science,” scientist Yaneer Bar-Yam, president of the New England Complex Systems Institute recently tweeted.
“Right now, everything that we’re seeing suggests that herd immunity is just not possible” Razak said. What we may find is that we are exposed to enough variants that we do start to develop the kind of immunity we see for typical influenzas or other coronaviruses we’ve experienced for years “where you don’t have these enormously disruptive infections that we’re seeing now,” infections that are draining staffing levels in hospitals.
SARS-CoV-2 may mutate into a very mild version. People with Omicron often report a sore throat, hoarse voice, cough, headache. “If that’s the case moving forward, it’s endemic as a nuisance more than anything,” Snutch said, “though a nuisance in older people can be deadly, just like the flu is deadly.”
A catastrophic variant can’t be ruled out, he said. “But the way the virus is going, it has spent a lot of ammunition already in mutating its spike protein,” the studs on the surface of SARS-CoV-2 that the virus uses to latch onto human cells. “As a scientist, one has to wonder where it would go.… We can’t predict with any certainty what those mutations would be to cause it to be much more virulent again. I’m not an evolutionary biologist, but it may have gone down that path as far as it can go.”
In July, the country is in its seventh wave, and its third bout with Omicron. Ontario is expected to peak in the coming weeks. More hospital admissions mean more pressure on overstretched emergency rooms, where people are already sleeping on blankets on the floor. Repeat infections, according to Public Health Ontario, increase the risk of all-cause mortality (death from any cause) hospitalization and other serious outcomes. “The risk and burden may increase in a graded manner according to the number of infections,” the agency said in its latest situation update. It’s not clear whether repeat infections boost the risk of long COVID, the long tail after infections subside. Hankins wonders, “What are we carrying forward?”
Revived calls in some quarters to restore masking mandates in public transit and crowded indoor public spaces have been met with: “not a contingency for the present” (Ontario chief medical officer of health Dr. Kieran Moore) and, “At this point … we’re not having that conversation” (New Brunswick’s CMOH Dr. Jennifer Russell).
The “it’s over” narrative might explain why researchers aren’t yet seeing the participation rates they’d hoped for in a national antibody survey. A total of 100,000 randomly selected adult Canadians were sent questionnaires and dried blood sample collection kits this spring, to see how many are still showing antibodies from vaccines, infections, or both, whether they had symptoms of COVID and how many of those symptoms are persisting (estimates for long COVID are all over the map, ranging from three to 20 per cent of cases, infections that can take months to resolve, if they do resolve). With so little testing being done, researchers also want to try to assess “just how big the current wave is,” Hankins said. How many asymptomatics are walking around, infecting others? (According to the Worldometers website, there were 272,926 currently infected Canadians Thursday.)
For people wondering whether to hold out until the fall for a fourth dose, hoping for boosters containing BA.4 and BA.5, Hankins’ advice, particularly for those who are older or immunocompromised is not to wait until the fall when transmission has picked up. “Transmission has picked up. It’s up, now.”
Lockdowns and other draconian measures aren’t necessary. But, “What is the core strategy that will allow Canadians to live as full a life as possible while protecting the things we value, including our elderly and most vulnerable,” Razak asked. “The compromise may be that we accept that we have to invest in air quality, and we have to wear masks during periods of high viral spread and keep updated with vaccines to the best extent possible.”
We’ve treated COVID as the most important health issue of the day for the past two years, “and maybe rightly so for a chunk of that,” says Dr. Sameer Elsayed, an infectious diseases specialist at Western University.
“But we can’t really be too focused on COVID at the expense of so many other things that we’ve just ignored over the years.” Delays in cancer surgery. A “humongous” wait list for medical care for just about anything.
He’s not entirely convinced a fourth shot results in any meaningful benefit. But stubborn variants are making vaccinology challenging.
“None of us, in our lifetimes, have seen any virus that behaves this way,” Elsayed says.
“I don’t think anybody can predict what we’ll be facing in the future.”
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