National Post (National Edition)
Canada may be at the dawn of COVID-21
The growing threat from viral mutants is dampening hopeful signs that the COVID-19 pandemic in Canada is coming under control.
While Canada is registering 4,000 fewer daily confirmed cases, on average, than the country was seeing three weeks ago, while hospitalizations and deaths are on the decline, scientists are warning aggressive efforts are needed to slow the spread of COVID variants coming in from other places — or new “Canadian” mutations emerging from here.
Mutations from South Africa and the United Kingdom are already circulating inside Canada. More than 135 cases of the U.K. variant, and at least 30 of the South African, have been reported across Canada. The true number isn't known because only five per cent of positive COVID-19 tests are now being screened for the variants. The goal is to ramp up to 10 per cent and tighten turnaround time for results.
While daily case counts and “severe outcomes” are declining, “there is still a lot of infection in our communities, and we must hold fast to these measures to prevent acceleration of the epidemic and limit spread of variants,” Canada's Chief Public Health Officer Dr. Theresa Tam said Tuesday.
Ongoing high infection rates in some parts of the country mean that viral evolution is running at high speed and, given enough time, new mutations could inevitably emerge at home, said Amir Attaran, a biologist and professor of health law at the University of Ottawa.
Meanwhile, the U.K. strain is further mutating, suggesting the virus may be adapting to dodge the human immune response, scientists said.
Public Health England reported this week that a fraction — just 11 — of some 200,000 samples tested of the contagious U.K. variant, the same one now circulating in Canada, showed a mutation called E484K.
The mutation — also shared by the South African and Brazil variants, and the one causing the most concern — “causes some loss of sensitivity to immune responses that give protection against virus infection,” according to Dr. Jonathan Stoye, of the Francis Crick Institute. In lab studies, antibodies were less able to bind to the spike protein coating the virus to keep it from entering cells.
A U.K. variant bearing the E484K mutation hasn’t yet been detected in Canada.
But viruses mutate and shift, sometimes randomly, and sometimes because of pressure in the environment. The more mutations, the greater the risk the virus is able to reinfect people and transmit even more widely, said University of Manitoba virologist Dr. Jason Kindrachuk.
“We have to remember that this virus just got introduced to humans very recently in its history — it’s still figuring out how to transmit from human to human,” said Kindrachuk, Canada Research Chair in emerging viruses.
“A year into this, it’s now starting to see there are competitive advantages in certain mutations.
It seemingly is picking up different mechanisms to be able to deal with us as human hosts.”
The U.K. variant has been tied to an explosive spread of COVID-19 at a Barrie, Ont., longterm care home that has killed 61 residents. Two cases of the variant have been confirmed in an outbreak of COVID at a meat processing plant in North York. Eighty staff and students at a Maple Ridge, B.C. high school are being mass tested after possible exposure to the U.K. variant, while health officials in Ontario have warned the variant will become the dominant strain of the pandemic virus by mid-March.
“The question that the world faces in early 2021 is whether these new variants will escape recognition by vaccine-induced immunity,” American virologist John P. Moore of Cornell University, and Dr. Paul Offit, a vaccine adviser to the U.S. government and Children’s Hospital of Philadelphia pediatrician write in JAMA.
Both Pfizer/BioNTech and Moderna have reported that their vaccines appear to work against the U.K and South African variants, based on blood samples taken from people who have been vaccinated. Pfizer said preliminary findings “do not indicate the need for a new vaccine to address the emerging variants.”
The Novavax vaccine is 86 per cent effective against the U.K. variant, and 60 per cent against the South African, the British Medical Journal (BMJ) reported last week.
The U.K. variant spread rapidly, within weeks. But the U.K. has seen its curve fall with more stringent public health measures.
Approved vaccines “are still showing good efficacy” against the variants, McMaster University immunologist Dr. Charu Kaushic, a member of Canada’s COVID immunity task force, told a media briefing Tuesday. “I don’t think that is a worry right now, but that’s definitely something to keep an eye on.”
Technically known as B. 1. 1. 7, the U.K. variant is believed about 50 per cent more transmissible than the current dominant strain. While it’s not more lethal, it could drive dramatically higher case counts.
Dr. Guillaume Poliquin, of the National Microbiology Laboratory, said a network of labs is working to increase the amount of test samples genetically sequenced, including samples from potential “super spreading” events.
But having that genetic data “fails entirely if you still have slow, or absent, contact tracing and case isolation,” Attaran said. “Identifying new strains as more dangerous is only going to make a difference if you do something about each such case immediately.”
One strategy is “ring fence” vaccination — immediately vaccinate everyone in contact with people carrying variants to kept them from spreading further. “But since we can’t even trace those persons in Canada’s broken-down systems, and we have no vaccine kicking around, it’s a nice idea which we can’t really implement,” Attaran said.