As Omicron reveals, Canadian scientists scramble to predict its impact on populations at risk
Not the idea of ââa Christmas present in advance, but what Anne-Claude Gingras wants most right now is a good batch of Omicron variant proteins.
They may come from samples of the COVID-19 variant that have been obtained and cultured from Canadian cases of Omicron. Or they can be synthesized from scratch using an RNA model that mimics Omicron’s genetic sequence – now available to researchers around the world.
Either way, once Dr. Gingras has the proteins in hand, her goal is to combine them with blood samples taken from long-term care Ontario residents who have received their third dose of ‘a COVID-19 vaccine.
âThis is the same cohort that we established against Alpha, Beta, Gamma and Delta,â said Dr. Gingras, principal investigator at Mount Sinai Hospital in Toronto. âWe want to make sure that we can provide counseling to this supervulnerable population. “
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Evidence from countries where Omicron is spreading, particularly South Africa, suggests that it is better at evading vaccines than worrying previous variants and that it will produce more breakthrough infections.
A priority for Dr Gingras and his colleagues is to see if it can replicate the lab results reported Wednesday by Pfizer and BioNTech which show that the companies’ vaccine is still resistant to Omicron in people who have received a booster.
If this turns out not to be the case for those at high risk, long-term care facilities may require more stringent measures to thwart outbreaks, including rapid testing and restrictions on the number of visitors.
âThere is a list of things we need to think about in long-term care,â said Allison McGeer, a physician and infectious disease researcher who is co-leading the Mount Sinai cohort study. âSome, we might want to start doing it now to minimize the damage. And some that we want to be ready to activate when we recognize we need them. “
Ultimately, Omicron could accelerate the need for fourth doses for long-term care residents and possibly antiviral drugs as a preventative measure, Dr. McGeer said. Meanwhile, Omicron’s impact on the general population remains more difficult to discern.
The latest technical report on COVID-19 variants from the UK health agency predicts that Omicron cases will reach parity with cases caused by the previous Delta variant later this month. In Canada, modeling studies presented by public health director Theresa Tam on Friday show the potential for a sharp rise in cases in mid-January if Omicron becomes established.
Such a peak would be exacerbated by the improved ability of the variant to move among vaccines and produce infections at a higher rate. In doing so, it would more easily find the remaining unvaccinated and fully susceptible population. Too sudden an acceleration in COVID-19 in this one group alone would be enough to push Canadian emergency rooms to breaking point, epidemiologists warn.
The silver lining may lie in indications in South African data that Omicron produces a milder form of the disease in many of those who contract it. Although the results are preliminary, it’s something many experts have commented on, including Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases and chief medical adviser to the White House.
Dr McGeer said there are several important differences that make it difficult to extrapolate South African data to predict Omicron’s impact in Canada.
For starters, South Africa’s population is younger, which on average reduces the risk of severe COVID-19. The country also had a much higher infection rate in previous waves of the pandemic, including a second wave dominated by the beta variant, which shares some of Omicron’s mutations. This variant has had little impact in Canada due to the overwhelming prevalence of the Alpha and Delta variants.
In comparison, Canada may not be as well prepared for a variant with the particular characteristics of Omicron despite a higher vaccination rate. And while Omicron continues to have lower disease severity per individual case, this benefit may be offset by a larger total number of cases.
A more speculative question is how Omicron may change the nature of the pandemic in Canada after the peak of its initial wave.
Jane Heffernan, a mathematical epidemiologist at York University in Toronto, said if Omicron was found to be more communicable but less severe, it could accelerate the transition from COVID-19 to an endemic disease. Over time, it would start to look like the seasonal flu or – at best – the milder coronaviruses associated with the common cold. Such a future fits with the evolutionary principle that viruses benefit when they can easily infect individuals but do not prevent people from circulating among others and spreading the virus further.
Sarah Otto, a theoretical biologist at the University of British Columbia, warned that this reasoning may not apply to COVID-19, a disease in which severe consequences and death tend to occur long after the virus had the opportunity to spread to others.
However, said Dr Otto, there is another way to look at why the variant may have lower severity.
Earlier variants are believed to have arisen in immunocompromised individuals, where mutations helped them thrive and overcome a weakened immune system. If the same process gave birth to Omicron, which has many more mutations than other worrisome variants, it may have continued to evolve in a single host for months in order to accumulate so many changes. But that would only be possible if the host was able to live with the virus rather than succumb to it.
“We have to think about what this variant has been chosen to do in someone for six months or a year,” said Dr Otto. “If he had been very serious, this individual might not have survived long enough to pass it on.”
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