National Post (National Edition)
COVID-19 variants evolving, spreading quickly
In extreme cases of COVID-19, the lungs can become rigid, heavy, shrinking to half their size. Instead of salmon pink and spongy, they look more like livers.
It's not yet known whether the new variants pose a more perilous threat to lung tissue. A variant has swept through the Vancouver Canucks, benching healthy, young athletes with usually remarkable lung stamina. Doctors are reporting younger people arriving in ICUs needing ventilation or artificial lung support. “It's hard to tell if the variants will cause more permanent lung damage,” said Dr. Marcelo Cypel, Canada Research Chair in lung transplantation at Toronto's University Health Network.
Like so much of this moment — the “old” COVID-19 fading, a “new pandemic” surging in parts of the country — “I don't think we can say that yet,” Cypel said.
Canada is in the supremely unenviable position of battling surging infections caused by three daunting variants: the B.1.1.7 variant first found in England, the P.1 or Brazilian variant first identified in Japan in travellers returning from the Amazon, and the B.1.351 variant that emerged in South Africa. P.1 is gathering steam in British Columbia, while Ontario, now in its third stayat-home state of emergency, has ordered hospitals to halt all non-urgent surgery and could soon enact a critical triage protocol that, should the variants push hospitals to crisis levels, could have random selection determining who ultimately gets the empty ICU bed.
Where will this virus go? How much of a threat are the variants? What mutations might arise in the future? And will the vaccines save us in time?
Across Canada, experts are monitoring the evolutionary trajectories of the variants, giving advice to governments.
The SARS-Cov-2 virus is still adapting to humans. Viruses may not have a brain, “but they're governed by the same evolutionary drive that all organisms are — their first order of business is to perpetuate themselves,” University of Connecticut virologist and vaccinologist Paulo Verardi wrote in The Conversation. The more people infected, allowing the virus to propagate, the greater the probability of new variants of concern emerging.
Rattling nerves is evidence that, not only are they more transmissible, spreading more easily, and quickly, the Brazilian and South African variants can potentially evade antibodies produced through natural infections or vaccines.
The vaccines being deployed across Canada still offer immunity against the variants. They all prevent hospitalization and death.
“They work, and we have to get them out,” said University of Ottawa virologist Marc-André Langlois. Reduce the pool of people that are infected, and the virus has fewer opportunities to create new progeny and generate new variants.
“If variants continue to evolve, that's when we're going to run into problems,” particularly with the South African and Brazilian variants, said Langlois, lead of Canada's Coronavirus Variants Rapid Response Network. “If those variants continue to evolve, they could evolve into something that is vaccine-resistant.”
Almost 25,000 variant cases have been reported across Canada. On Jan. 12, there were officially 22. Even as vaccines bring us closer to the end of the crisis, “We cannot afford to give the virus an inch,” Canada's chief public health officer Dr. Theresa Tam said Friday.
Among the worrying trends, the number of people experiencing severe and critical sickness is rising, including younger and previously healthy adults.
It's not clear whether the variants have a higher biological affinity for younger people, but a new preprint is linking the P.1 variant to a sudden and dramatic spike in COVID-19 deaths among younger adults in the south of Brazil. “All groups above 20 years of age showed statistically significant increases in CFR (case fatality ratio, the proportion of deaths among confirmed cases) when diagnosed in February 2021 as opposed to January 2021,” the researchers reported. Those aged 20 to 29 saw a tripling of their CFR, from 0.04 per cent to 0.13 per cent; for those 30 to 59, the CFR roughly doubled.
P.1 could become the predominant variant in many jurisdictions in Canada, depending on policy decisions. “The science has been saying for some time that the VOCs (variants of concern) are more dangerous, but health policies are tending to follow rather than lead,” said Dr. Terrance Snutch, chair of the Canadian COVID-19 Viral Genomics Network.
All three of the main variants have mutations in their spike protein gene, some unique to each one, others shared between all three. The spike protein studs SARS-CoV-2's surface. It's what the virus uses to bind to the human ACE2 receptor and enter our cells.
“That shared mutations have arisen independently from across the world suggests that the virus is showing convergent evolution. In other words, there are only so many moves that the virus is capable of making regarding altering its spike protein and still be infectious, replicate and then go on to infect additional people,” Snutch said.
But evolution has its limits. “Sooner or later the virus is predicted to run out of options regarding mutating its spike protein — the route of infection into human cells,” Snutch wrote in an email.
Many thousand mutations distinct from the original Wuhan virus have been identified from samples from people who have tested positive across the country. While a portion could be considered “variants of interest,” Snutch said, none have so far reached the status of a “variant of concern.” What makes a VOC? It spreads more easily, makes people sicker and has the ability to dodge neutralizing antibodies induced by vaccines.
The vaccines available can elicit a broad immune response that includes not just antibodies but memory cells. Mutations in the virus shouldn't make vaccines completely ineffective, and manufacturers have said they can tweak the composition of their vaccines to protect against the variants.
But most of the country remains unvaccinated. Ontario Premier Doug Ford has promised to have 40 per cent of adult Ontarians vaccinated by May 6. Quebec Premier Francois Legault's goal is for all adult Quebecers who want one to get a COVID-19 shot by June 24.
One challenge could be vaccine hesitancy. How many Canadians will decline the vaccine? The larger that proportion, the greater the probability of the virus continuing to spread and evolve. “We need to reach out to the hesitant, showing them safety data. If you get infected with the virus you have a much higher probability of being critically ill than any probability of a vaccine side effect,” Langlois said.
The variant currently reigning supreme in Canada — B.1.1.7 from the U.K., which now accounts for 90 per cent of the variants, is already slightly more deadly, and “there's a reasonable possibility it could even get worse,” University of Oxford professor of evolution and genomics Aris Katzourakis told New Scientist.
Variants have emerged in New York City, California, Paris, London. What we're seeing is still evolution, Langlois said, but nothing so far is as problematic at the Brazilian and South African strains.
“For virologists, the worst case scenario is that the current variants jump back in their animal reservoirs, recombine with other coronaviruses and come out with a new strain of something that the vaccines won't work on,” he said.
There are hundreds of coronavirus strains in bats, believed to be the origin of SARS-CoV-2. “With deforestation and climate change, humans and wild animals are coming in closer contact, and these zoonotic exchanges are being seen more and more frequently,” Langlois said.
It's not known how long vaccine-induced immunity will last. “One shot you don't fall sick, with two shots you don't make anyone else sick,” Langlois said. People infected with SARS-1 still show immunity. “Once a large proportion gets both vaccines, we will see the numbers drop,” Langlois said. Reinfection will happen. People will fall sick, but they won't end up in the ICU.
Snutch doesn't believe herd immunity will be easily achieved. The long-term effectiveness of the first generation of vaccines isn't known. The virus will continue to circulate in the non-vaccinated, here and throughout the world, he said.
“At some point in time, one of those infected people is going to generate a new (variant of concern) that sufficiently avoids the current vaccine-driven immune responses, and when that person gets on a cruise ship or plane” the new variant could spark its own pandemic.
The virus will likely keep mutating enough that we'll need a booster shot every year or two, an outcome Snutch said is “likely OK.” The vaccines could be tweaked again to be protective against death. “One could predict that future infections of vaccinated people to be more along the lines of bad colds/flus,” he wrote.