Canadian scientists discover new COVID-19 variant in deer that may spread to humans
The study presents what may be the first documented case of deer-to-human COVID-19 transmission, recorded in Ontario
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By Kevin JiangToronto Star
Tue., Nov. 15, 2022
Researchers have discovered a “highly divergent” variant of COVID-19 in Canadian white-tailed deer — and it’s already been detected in at least one person.
The study, published Nov. 10 in journal Nature Microbiology, might represent the first ever documented case of deer-to-human COVID-19 transmission, according to one of the study’s authors.
The variant, named B. 1.641, was detected in late 2021 from the nasal swabs of five white-tailed deer in southwestern Ontario. Around the same time, a “highly similar” genetic sequence to the variant was found in a human in Ontario, the paper read, suggesting that person caught it from a deer.
The Public Health Agency of Canada (PHAC) confirmed the incident, stating the person “appears to be an isolated case with no further transmission.”
According to Brad Pickering, the first author of the paper and a research scientist at Canada’s National Centre for Foreign Animal Disease, exactly how the person contracted the virus remains unclear.
“Obviously it’s rare because, you know, we’re only seeing one (case) out of all of these things we surveilled,” Pickering told the Star.
Pickering’s team of collaborators from across Canada have been monitoring 20 species including skunks, raccoons and bats since the summer of 2020, but this study was the first evidence they’ve seen of non-human spread in the wild.
“I don’t think we necessarily have to be overly concerned about (this exact variant),” Pickering said. “it’s not going to be this huge public health threat. But I think it’s informative to know that there’s a potential risk for viruses to be maintained in wildlife.”
According to Pickering’s paper, this deer variant descended from the B. 1 version of the virus — which circulated about a year ago — and has 76 mutations compared to the original COVID-19 strain. That’s more than the currently dominant Omicron BA. 5 variant, which has over 50.
Unlike Omicron, and despite nine of the deer variant’s mutations being on the spike protein — the feature of the COVID-19 virus targeted by major vaccines — B. 1.641 was effectively wiped out by blood samples of people either vaccinated two to three times or who have already recovered from infection, the study found.
“The interesting part is … we think because there is so many changes — there is about 76 changes to the virus — we’re thinking that it was probably circulating in deer for a long period of time, almost a year,” Pickering told the Star. “And a year for (the COVID-19 virus) is a long time.”
This potentially means older variants of the virus could keep evolving in animals like deer and minks, then eventually leap back into humans with new functions and abilities, Pickering said.
The human-to-animal spread of COVID has been well-documented — we know of at least 54 mammal species that are susceptible, the paper reads. However, viral spread from animals back into humans is much rarer. Minks were the first and, until now, potentially only example, according to PHAC.
According to Sarah Otto, head of the BC COVID-19 Modelling Group and a professor of evolutionary biology at the University of British Columbia unaffiliated with the study, just because a virus might leap from animals to humans, doesn’t mean it’s able to then spread from human to human.
“I am not particularly concerned about this lineage because there has not been documented spread from human to human,” Otto said.
Like Pickering, she primarily found the study “eye-opening” for documenting COVID-19’s spread within animal species in the wild. Most of our previous non-human cases were in domesticated animals, like minks, she said, which were kept in high densities where disease could spread.
“I think that this study was really eye-opening for demonstrating that not only is the virus spread among deer, but it’s evolving in its own direction within deer,” she continued.
There are two possibilities for how this strain might evolve over time, Otto said: “It could be evolving to specialize in deer and actually be very poorly replicating in humans.
“Alternatively, it can evolve different capacities and different ways of infecting cells that are still functional in humans, and jump back into humans, which is the worst (outcome).
“It’s too early to tell, but I think in general, having many large reservoirs of this virus in animals is bad news,” she said. “The more opportunities for this virus to evolve and jump back into humans, the worse it is.”
In a news release, Dr. Samira Mubareka, a corresponding author of the paper and an associate professor at U of T’s Temerty Faculty of Medicine, said “I was not expecting to find this highly divergent virus.”
By Kevin JiangToronto Star
Tue., Nov. 15, 2022
Researchers have discovered a “highly divergent” variant of COVID-19 in Canadian white-tailed deer — and it’s already been detected in at least one person.
The study, published Nov. 10 in journal Nature Microbiology, might represent the first ever documented case of deer-to-human COVID-19 transmission, according to one of the study’s authors.
The variant, named B. 1.641, was detected in late 2021 from the nasal swabs of five white-tailed deer in southwestern Ontario. Around the same time, a “highly similar” genetic sequence to the variant was found in a human in Ontario, the paper read, suggesting that person caught it from a deer.
The Public Health Agency of Canada (PHAC) confirmed the incident, stating the person “appears to be an isolated case with no further transmission.”
According to Brad Pickering, the first author of the paper and a research scientist at Canada’s National Centre for Foreign Animal Disease, exactly how the person contracted the virus remains unclear.
“Obviously it’s rare because, you know, we’re only seeing one (case) out of all of these things we surveilled,” Pickering told the Star.
Pickering’s team of collaborators from across Canada have been monitoring 20 species including skunks, raccoons and bats since the summer of 2020, but this study was the first evidence they’ve seen of non-human spread in the wild.
“I don’t think we necessarily have to be overly concerned about (this exact variant),” Pickering said. “it’s not going to be this huge public health threat. But I think it’s informative to know that there’s a potential risk for viruses to be maintained in wildlife.”
According to Pickering’s paper, this deer variant descended from the B. 1 version of the virus — which circulated about a year ago — and has 76 mutations compared to the original COVID-19 strain. That’s more than the currently dominant Omicron BA. 5 variant, which has over 50.
Unlike Omicron, and despite nine of the deer variant’s mutations being on the spike protein — the feature of the COVID-19 virus targeted by major vaccines — B. 1.641 was effectively wiped out by blood samples of people either vaccinated two to three times or who have already recovered from infection, the study found.
“The interesting part is … we think because there is so many changes — there is about 76 changes to the virus — we’re thinking that it was probably circulating in deer for a long period of time, almost a year,” Pickering told the Star. “And a year for (the COVID-19 virus) is a long time.”
This potentially means older variants of the virus could keep evolving in animals like deer and minks, then eventually leap back into humans with new functions and abilities, Pickering said.
The human-to-animal spread of COVID has been well-documented — we know of at least 54 mammal species that are susceptible, the paper reads. However, viral spread from animals back into humans is much rarer. Minks were the first and, until now, potentially only example, according to PHAC.
According to Sarah Otto, head of the BC COVID-19 Modelling Group and a professor of evolutionary biology at the University of British Columbia unaffiliated with the study, just because a virus might leap from animals to humans, doesn’t mean it’s able to then spread from human to human.
“I am not particularly concerned about this lineage because there has not been documented spread from human to human,” Otto said.
Like Pickering, she primarily found the study “eye-opening” for documenting COVID-19’s spread within animal species in the wild. Most of our previous non-human cases were in domesticated animals, like minks, she said, which were kept in high densities where disease could spread.
“I think that this study was really eye-opening for demonstrating that not only is the virus spread among deer, but it’s evolving in its own direction within deer,” she continued.
There are two possibilities for how this strain might evolve over time, Otto said: “It could be evolving to specialize in deer and actually be very poorly replicating in humans.
“Alternatively, it can evolve different capacities and different ways of infecting cells that are still functional in humans, and jump back into humans, which is the worst (outcome).
“It’s too early to tell, but I think in general, having many large reservoirs of this virus in animals is bad news,” she said. “The more opportunities for this virus to evolve and jump back into humans, the worse it is.”
In a news release, Dr. Samira Mubareka, a corresponding author of the paper and an associate professor at U of T’s Temerty Faculty of Medicine, said “I was not expecting to find this highly divergent virus.”
Mubareka explained that because humans are often in close contact with deer populations, “including public interactions with wild deer and captive deer for farming, exhibition or hunting,” it may be easier for our diseases to spread within the species.
“For many communities, deer are important from both a food security and a cultural perspective,” Mubareka said.
“Usually when you find a new virus that has spread between species, you want to understand how hazardous it is,” she continued. “Our followup work is going to focus on what this virus does in human and animal cells, and how it transmits.”
The PHAC has updated its recommendations to hunters and trappers when handling game meat. Its website includes tips like cooking the meat to 74° C or 165° F internally; processing carcasses in a well-ventilated area with appropriate gloves and eye protection; wearing a mask when exposed to animal lung tissues and fluids; and more.
“Based on available information to date, animal-to-human transmission is likely very uncommon,” its website reads. “COVID-19 is mainly transmitted from human to human.”
In the future, Otto said she’d like to see more research on the impact of COVID-19 on wild animal populations.
“We’re taking a fairly limited snapshot of what’s going on because of the focus on this one species,” she said. “And so I think the question is, how many other species is this also happening to?”
Kevin Jiang is a Toronto-based digital producer for the Star. Follow him on Twitter: @crudelykevin
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