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As wave after wave of COVID-19 crashes over us, the hope is that we will eventually reach a point where the seasonality of the virus will make the pandemic easier to predict and overcome.
But with highly contagious new variants emerging and causing leaps around the world at different times – will we soon have a regular “COVID season”?
The pandemic does not follow a clear pattern in Canada, with waves crashing chaotically spring, will fall and winter over the last two and a half years, largely due to the abolition of public health measures and new options threatening immunity from vaccines and previous infections.
Different options have also caught states unprepared at unexpected moments (and sometimes missed them altogether), making it increasingly challenging to predict when and where COVID waves will hit.
“Let’s be honest, the virus is here, not us,” said Dr. Michael Gardam, an infectious disease doctor, medical director of infection prevention and control at Toronto Women’s College Hospital and chief executive of Health PEI.
“We are entirely at the whim of random evolutionary events and it’s really hard to predict.”
Different countries, different waves
Canada currently has an unpleasant combination of Omicron sub-variants – including BA.1, BA.2, BA.2.12.1 and BA.2.3 – feeding a continuing sixth wave after public health measures were widely repealed, despite more than 80 per cent of those vaccinated. Canadians and nearly half of the infected population.
The US avoided a big wave of BA.2 until the end of last month, however BA.2.12.1 is now rapidly becoming the dominant strain in almost a third of the new cases, while Europe is also struggling with a increase of subvariants BA.2 and the emergence of BA.4 and BA.5.
This is despite relatively high levels of vaccination, with slightly above two-thirds double vaccinated in the US and more than 70 percent in Europe and even higher levels of previous infection.
More than half of Americans were infected with the virus by February, according to new data from Centers for Disease Control and Prevention in the United Stateswhile This was announced by EU representatives between 60 and 80 percent of the European population had COVID-19.
“It’s going to be harder and harder to compare countries,” and honestly, even before that, it was kind of hard, “said Deepta Bhatacharya, an immunologist at the University of Arizona.
“The alpha wave really hit the UK and it didn’t actually show up here, and I don’t know why. It was certainly introduced here and did not spread to the same extent and I have no idea why. So there are all kinds of things that make it difficult to understand and predict. “
People walk around Toronto’s Chinatown in March 2021. Canada currently has a nasty combination of Omicron sub-variants feeding the ongoing sixth wave after public health measures were widely repealed. (Evan Mitsui / CBC)
The immunity of the population can blunt future waves
Another factor that is difficult to predict is how the population’s immunity will change – and whether previous infections and high levels of vaccination will protect or reduce over time.
Tulio de Oliveira, director of the Center for Epidemic Response and Innovation in South Africa, said South Africa has a high level of immunity, with more than 90 per cent estimated to have been previously infected, vaccinated or both.
“This is one of the reasons we believe that the big Omicron wave we had did not lead to a very high number of hospitalizations and deaths,” he said.
“And BA.2, although it appeared and continues to dominate all infections in South Africa, did not lead to an increase in infections, which was very different in Europe, where they had BA.1, followed by BA.2.”
Omicron’s double strike of BA.1 and BA.2 hit Canada hard, fueling a devastating fifth wave late last year that subsided just as BA.2 triggered a smaller sixth wave in April – but also boosted our levels. per capita immunity.
“It gives you the feeling that the more people are infected and vaccinated, the better you can handle it,” Gardam said.
“The hope is that it will start to happen like the other coronaviruses that infect us every year and cause colds, and in the end it’s pretty hard for the virus to come up with something so new that you haven’t seen part of it before.”
As a result, Omicron and its sub-variants completely changed Canada’s immunity in the last few months.
Previously, Canada was more in line with a country like South Korea, given our high levels of vaccination and previously low levels of previous infection, de Oliveira said, with much of the country experiencing relatively low levels of vaccination. COVID during the pandemic.
With Omicron, we were more like countries like South Africa and the United States with much higher levels of immunity – but our high vaccinations protected us.
“This means that potentially, when new variants and sub-variants of Omicron appear, which can lead to a relatively large number of infections, but potentially not to a very high hospitalization and death rate,” he said.
“Look at the first wave, it was a very small wave, but there were a lot of hospitalizations,” Gardam said. “Then finally Omicron struck and the jump in infections was insane, but mortality has never been as high as in previous waves. So we’re getting better at fighting it.”
WATCH Canadians have called for booster vaccines for COVID-19 to fight the 6th wave:
Canadians call for booster vaccines against COVID-19 to blunt 6th wave
All indications are that Canada is going through the sixth pandemic wave, confirms Dr. Teresa Tam. Her message to Canadians: wear a mask and get stronger if you meet the conditions. 02:00
Gardam said the difference between provinces like Prince Edward Island and Ontario during the pandemic was that the maritime provinces that took COVID zero the approach had little existing immunity in the last two years.
But when Omicron struck in December, it took advantage of the province’s lack of immunity.
“It was just like thunder, here it is,” he said. “And it’s still going through the population, and yet we had tougher measures than Ontario and other provinces, but they went through all these different waves that we didn’t have.”
How will we get to the “COVID season” with constantly emerging options?
Although it is unclear whether the newly discovered levels of immunity in Canada and the persistently high levels of vaccination will repel future waves of the virus and bring us closer to seasonality, there are early hints from other countries that we may be able to anticipate more well the waves that will move forward.
Tom Wenselers, an evolutionary biologist at KU Leuven University in Belgium, told Twitter that South Africa is beginning to show signs of seasonality with COVID, which may seem like a “significant wave every six months with significant mortality and morbidity.”
BA.4 & amp; BA.5 The increase in new confirmed cases of Covid in South Africa, driven by Omicron sub-variants, gives a good idea of what the endemic balance will look like: a significant wave every 6 months with significant mortality & morbidity. 🧵 pic.twitter.com/I9jd5gMIPG
– @TWenseleers
“The impact on the health system of both BA.2.12.1 and BA.4 and BA.5 is not yet clear. They will certainly cause waves of infections, but the impact on hospitalizations and expected mortality cannot yet be assessed at this time, “he told CBC News.
“Early data seem to suggest a similar weight as the original Omicron in terms of hospitalization rates … but that’s a really early conclusion.”
de Oliveira, who led the research team that identified sub-options BA.4 and BA.5 in South Africa, said declining immunity to infection and vaccination could affect their spread.
“The only thing that can play a role in this is the exact time of the BA.1 wave, so we’re looking very closely at the data,” he said.
“We are talking about three or four months after the peak of BA.1 and we know that about three or four months are the times when population immunity begins to decline.”
New study for prepress co-author of de Oliveira, which has not yet been tested by partners, suggests that there may be “growth benefits” for BA.4 and BA.5 over BA.2 in South Africa, which could potentially trigger a new wave, but whether this will happen there or in other countries remains to be seen.
And more options are probably on the horizon.
“This just seems to be the behavior of SARS-CoV-2, and I don’t think we should be shocked to see another option,” said Alison Kelvin, a virologist at the Canadian Center for Vaccinology and the Vaccine and Infectious Diseases Organization. in Saskatoon.
“But also keep planning for them, unfortunately, which I think is affecting our vaccination strategies …” [an updated vaccine] there is a new option. “
People are battling the snow to line up for testing for COVID-19 in early January in Vancouver. The chaotic pattern of the Covid wave in Canada has not yet shown any serious signs of seasonal transmission, but there are some indications that we may eventually get there. (Ben Nelms / CBC)
Although the chaotic COVID wave model in Canada has not yet shown major signs of seasonality, there are some indications that I am moving towards it.
“There is still seasonality associated with COVID. That doesn’t mean it’s a perfect fit, but of course there are times during the colder months in Canada when we see more cases, “said Dr. Isaac Bogoch, an infectious disease physician at Toronto General Hospital.
“We hope this wave subsides and we have a great summer ahead of us.” but can this be broken with a very gear variant? Perhaps. Maybe. ”
Gardam said that if we look at other viruses in the long run, such as …
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