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With a virus still evolving, COVID-19 has not said its last word
In Europe, a new wave of COVID-19 is beginning and the same trend is emerging in Canada. While it is difficult to say precisely what awaits us over the next few months, one thing is certain:
the pandemic is not over and the presence of multiple variants of Omicron could have some surprises in store for us.
Melanie Meloche-Holubowski
Posted on October 9, 2022
For the past three weeks in the UK, the number of cases and hospitalizations has been rising rapidly. Over the past week, these have increased by 33%. More than 3,100 hospitalizations last week: this is the second week with the most in 2022.
In France, hospitalizations have increased by more than 40% for a week and the positivity rate is close to 25%, which indicates a very high community transmission.
In Canada, sewage analyzes in several cities show an increase in the concentration of SARS-CoV-2.
In Quebec, hospitalizations and the number of health care workers absent due to COVID-19 are increasing. In Ontario, the number of hospitalizations is climbing and has already almost reached its peak this year.
UK study co-founder Zoe COVID(New window), Tim Spector, told The Guardian(New window)that the fall is likely to be very difficult. We risk having a difficult month of October, which will probably be worse than the last wave.
Dr. Catherine Hankins, professor of public and population health at McGill University and co-chair of the COVID-19 Immunity Task Force, agrees. In addition to the lifting of the majority of health measures, several elements are present to cause a new wave.
Multiple variants blur the cards
According to Ryan Gregory, professor of evolutionary biology in the Department of Integrative Biology at the University of Guelph,
the situation is different this fall because of the proliferation of variants in circulation. We have never faced so many variants at the same time.
During the first waves, only one variant dominated. The first variants – like Alpha and Delta – hardly circulate anymore, since new, more competitive variants have taken their place.
Then, Omicron appeared. Omicron's original line, BA.1, first struck in January 2022. This strain now accounts for less than 1% of cases in Canada.
Since then, Omicron has been mutating at a rapid rate, producing an array of sub-variants. For example, BA.2 hit in the spring, followed by BA.4 and BA.5 this summer. Currently, approximately 2% of cases in the country are caused by BA.2, 10% by BA.4 and almost 90% by BA.5.
“ We observe that certain lines of Omicron mutate very quickly. Yes, the flu virus also mutates every year, but not at the rate of SARS-CoV-2. »
— A quote from Ryan Gregory, University of Guelph
In fact, according to Trevor Bedford, a virologist at the Fred Hutchinson Cancer Center, the rate of evolution of SARS-CoV-2(New window)one year is equivalent to five years of evolution of H3N2, one of the most frequently mutating flu viruses.
Currently, there are nearly a dozen variants competing to replace the BA.4 and BA.5, including BA.2.75, BA.2.75.2, BA.2.3.20, BA.4.6, BQ.1, BQ.1.1 and XBB. These are all Omicron variants , says Gregory.
Currently, the BA.4.6, BA.2.75 and BQ.1 subvariants are present in Canada.
A soup of variants capable of escaping immunity
What concerns Gregory is not only the amount of highly transmissible subvariants, but also the fact that they are becoming increasingly adept at escaping immunity acquired through infection or vaccine.
“ The virus is less and less interested in becoming more transmissible. It mutates to further evade our immunity and to infect again and again. We don't know exactly how this will all end, but we do know that several of these variants will evade immunity. »
— A quote from Ryan Gregory, University of Guelph
Additionally, some of these variants appear to counteract the effects of the handful of drugs that are available to treat and protect those at risk of serious complications from COVID-19. This is notably the case for sub-variants BQ.1.1 and BA.2.75.2.
Will these subvariants cause more serious complications? It's hard to say at this point, says Gregory. Health Canada advises that
although Omicron has been widely associated with less severe disease compared to previous variants, the virulence of the BA.4 and BA.5 sublines is currently unclear .
Can we rely on hybrid immunity?
Since two-thirds of Canadians would have been infected(New window)since last December, authorities have increasingly mentioned hybrid immunity – that is, immunity acquired by infection in a vaccinated person.
Could this hybrid immunity help reduce the repercussions of a new wave? Impossible to know for sure.
Health Canada warns that the duration of hybrid immunity has not yet been fully characterized .(New window).
But in a study published this week, but not peer-reviewed(New window), it was sought to understand whether an infected person should also be vaccinated. The researchers compared protection against infection and against severe disease between infected and unvaccinated people, vaccinated and uninfected people, and people with hybrid immunity (infected and vaccinated).
"Our results clearly indicate the need for vaccination, even among people who have already been infected ," said one of the study's authors, Dr. Niklas Bobrovitz.
In all three groups, protection against hospitalization and serious complications remains high after six months: 95% protection with hybrid immunity; 80% with infection without vaccination; and 65% with the first doses of the vaccine without infection. In people with hybrid immunity, protection against complications lasts at least 12 months.
As for the protection against reinfections, it decreases rapidly from six months for the three groups. Finally, infection with one of the Omicron subvariants reduces the risk of reinfection with another Omicron subvariant. However, Dr. Bobrovitz clarified that it is too early to know if this applies to all new subvariants.
The researchers are clear: Knowingly acquiring an infection in the hope of having hybrid immunity is not recommended.
“ The risks [associated with COVID-19 infection] are significant and it would be unwise to ignore them. »
— A quote from Dr Maria Van Kerkhove, technical lead for the management of the COVID-19 epidemic at the WHO and author of the study
These include the risks of hospitalization, admission to intensive care, need for mechanical ventilation and death. There is also the risk of developing post-COVID-19 syndrome . Additionally, those who survive severe COVID-19 have an increased risk of cardiovascular complications, dementia, diabetes and chronic respiratory disease , the study authors write, adding that vaccination remains a safe way to avoid the serious consequences of the disease.
Like the study authors, Gregory asks people to take all necessary precautions to avoid many infections.
“ We don't know what happens if you get infected 3, 4, 5, or 6 times. We don't fully understand the long-term impacts of reinfections. But we know that each reinfection increases the risk of complications. »
— A quote from Ryan Gregory, University of Guelph
Mr. Gregory does not believe that governments should rely exclusively on hybrid immunity , since the virus evolves too quickly. He points out that authorities relied on the fact that millions of Canadians were infected last winter to have a calmer summer. Quite the opposite happened.
Dr. Kerkhove clarified that hybrid immunity alone will not end the pandemic.
“ Waves of infection will continue to occur even when hybrid immunity levels are high, because current vaccines do not completely prevent infection – that is not the primary goal of vaccines. »
— A quote from Dr. Maria Van Kerkhove, technical lead for the management of the COVID-19 epidemic
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https://ici.radio-canada.ca/nouvelle/1922953/pandemie-covid-variants-omicron-coronavirus-vague
