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Do we dare hope COVID-19 is becoming milder with Omicron? ‘Hope isn’t science’

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While lower severity to Delta could be a good thing, the benefits could be washed away if Omicron spreads more easily or is better able to elude some immunity

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Sarah Otto’s hope, her “dream scenario,” is that the Omicron variant does prove milder, that the variant rattling nerves, airlines and stock markets causes only mild disease, as some early anecdotal reports would suggest.

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“That would mean let it run,” the University of British Columbia evolutionary biologist said. “Let it run its course and reach the world.”

“For the unvaccinated, mild COVID could train the immune system, much like vaccines,” Otto said. “For the vaccinated it would be like a natural booster.”

But she is ever so cautious. “I dare not even hope,” she said. “Hope isn’t science.”

There are now reports of toddlers in hospital with Omicron , and while some South African doctors have said the cases they have seen appear mostly mild , with fever, cough and aches and pains, those cases involved mostly younger adults — university-aged students and people healthy enough to get on a plane. Not the medically fragile.

And while lower severity to Delta could be a good thing, the benefits could be washed away if Omicron spreads more easily or is better able to elude some immunity from vaccination or past infections.

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“Maybe it causes half the amount of hospitalizations and deaths,” Otto said. But if there are many more infections, “that’s still a lot of hospitalizations and deaths.”

Viruses new to humans tend to cause more severe disease at the early stages of an outbreak or pandemic, partly due to the fact we don’t have pre-existing immunity, said Matthew Miller, an associate professor of infectious diseases and immunology at McMaster University in Hamilton.

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“For viruses to evolve to become less severe there needs to be ‘selective pressure,’” Miller said in an email. If, like SARS-1, people get very sick, very quickly, they are less efficient spreaders, because they’re too sick to go out in public. The virus peters out. But viruses aren’t thinking animals. “They don’t ‘care’ about how sick they make people, as long as they can spread,” Miller said.

With SARS-CoV-2, people can spread the virus quite efficiently already, even if they aren’t yet showing symptoms or never do, meaning “it’s not clear that there’s much pressure on the virus to cause less severe illness,” he said.

Overall, SARS-CoV-2 already causes fairly mild symptoms in most, though not for the elderly or those with chronic health problems, “and when there are high caseloads, the number of severe illnesses increases,” Miller said.

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It will take weeks before scientists get a firm handle on how Omicron compares to Delta in terms of severity of disease, he and others said.

South Africa also has a high background of immunity: Studies suggest 40 to 50 per cent of South Africans were exposed to SARS-CoV-2 in earlier waves. One paper estimated that the number of infections was likely 7.8-fold higher than recorded cases. That immunity, combined with vaccination, could be providing protection against serious disease, which could help explain why Omicron infections so far appear milder.

What concerns scientists is that Omicron has a surprising number of mutations on the spike protein adorning the surface of SARS-Cov-2, especially the part that the virus uses to glob onto the cells in our bodies and that authorized vaccines target. Three changes in particular each make the spike better able to bind to our cells, more magnetic. “We’ve seen some of these three mutations in different variants of concern,” Otto said, but none before Omicron have all three. “When my colleagues saw that they were like, ‘Uh, oh.’”

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Seven cases of Omicron had been confirmed in Canada as of Wednesday. Cases have been reported in Belgium, the Netherlands, France, Germany, Portugal and Italy and the United Kingdom.

At this point I give it about a 50-50 chance of being more or less severe. That’s how unsure science is at the moment

It’s not clear where or when Omicron first separated off from other SARS-CoV-2 variants, but it may date back to 2020. “It could be in a population that was so isolated that Omicron evolved there and it never got out until now,” said Otto, a professor in UBC’s department of zoology.

It may also have been living within one or two immunocompromised people unable to clear the virus. SARS-CoV-2 can reproduce to high loads, or linger much longer, in people with immune systems weakened by malnutrition, unclean drinking water, untreated HIV and other conditions, Miller said. And the longer the virus hangs around in the body the more opportunities to accumulate mutations.

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“It’s possible that Omicron has been hiding out for most of 2021 inside somebody,” Otto said. “That would suggest that all these changes in the spike that we’re seeing actually weren’t selected to help transmit from person to person,” she said. “They were selected to survive and propagate within that person’s body.”

And if that’s the case, it’s possible Omicron selected to be less severe, “so that it didn’t kill that individual, and that individual was able to move around and eventually infect somebody else,” Otto said.

“But we really have zero idea. At this point I give it about a 50-50 chance of being more or less severe. That’s how unsure science is at the moment.”

While Omicron has a jumble of mutations in the spike protein, “there’s still a lot of spike that’s not changed, and our immune reactions should recognize other parts well if we’ve been vaccinated,” Otto said. “But it will spread like wildfire among the unvaccinated.”

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Article content

While Moderna’s chief told the Financial Times this week he’s anticipating a “material drop” in vaccine efficacy, Otto is more optimistic. With a high vaccination rate, “we’ve got a base of immunity, and it’s not like (Omicron) has changed at hundreds of sites in the spike. It’s just changed at 30.” In the South African city of Tshwane, where Omicron was first detected, 87 per cent of hospital admissions are among the unvaccinated, The Guardian reported.

University of Manitoba’s Jason Kindrachuk: “We’re all trying to figure out very quickly what this is.”
University of Manitoba’s Jason Kindrachuk: “We’re all trying to figure out very quickly what this is.” Photo by Supplied

What Otto does find unnerving is that a fully vaccinated traveller who arrived in Hong Kong from Vancouver contracted the variant virus from another traveller from South Africa who was staying across the hall in the same airport quarantine hotel.

Though just one case, it could mean that Omicron is better able to transmit through smaller particles in the air, which would mean more longer-distance aerosol transmission, Otto said.

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If it can spread much more easily through the air, “and you need even smaller particles to get infected because it’s so good at getting inside our body, that is a game changer,” Otto said. “That’s my nightmare.”

Jason Kindrachuk is already losing sleep. “The last five days have been just chaos,” said Kindrachuk, a member of Canada’s coronavirus variants rapid response network. “We’re all trying to figure out very quickly what this is.”

Even if Omicron does cause milder infections, “the question is, how much milder would it have to be for us to be more comfortable,” asked Kindrachuk, Canada Research Chair in the molecular pathogenesis of emerging and re-emerging viruses at the University of Manitoba.

And even though Omicron does appear to have some transmission advantage, is it able to out-compete Delta, or is it going to fizzle out? “We don’t know,” Kindrachuk said. “Right now we don’t have any conclusive data to say anything.”

But while the focus is suddenly on Omicron, “we still have Delta circulating widely across the globe and making a lot of people sick and still causing a lot of fatalities,” Kindrachuck said. “We can’t lose sight of the situation we are already in.”

• Email: [email protected] | Twitter:

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While lower severity to Delta could be a good thing, the benefits could be washed away if Omicron spreads more easily or is better able to elude some immunity

Article content

Sarah Otto’s hope, her “dream scenario,” is that the Omicron variant does prove milder, that the variant rattling nerves, airlines and stock markets causes only mild disease, as some early anecdotal reports would suggest.

Advertisement

Article content

“That would mean let it run,” the University of British Columbia evolutionary biologist said. “Let it run its course and reach the world.”

“For the unvaccinated, mild COVID could train the immune system, much like vaccines,” Otto said. “For the vaccinated it would be like a natural booster.”

But she is ever so cautious. “I dare not even hope,” she said. “Hope isn’t science.”

There are now reports of toddlers in hospital with Omicron , and while some South African doctors have said the cases they have seen appear mostly mild , with fever, cough and aches and pains, those cases involved mostly younger adults — university-aged students and people healthy enough to get on a plane. Not the medically fragile.

And while lower severity to Delta could be a good thing, the benefits could be washed away if Omicron spreads more easily or is better able to elude some immunity from vaccination or past infections.

Advertisement

Article content

“Maybe it causes half the amount of hospitalizations and deaths,” Otto said. But if there are many more infections, “that’s still a lot of hospitalizations and deaths.”

Viruses new to humans tend to cause more severe disease at the early stages of an outbreak or pandemic, partly due to the fact we don’t have pre-existing immunity, said Matthew Miller, an associate professor of infectious diseases and immunology at McMaster University in Hamilton.

Advertisement

Article content

“For viruses to evolve to become less severe there needs to be ‘selective pressure,’” Miller said in an email. If, like SARS-1, people get very sick, very quickly, they are less efficient spreaders, because they’re too sick to go out in public. The virus peters out. But viruses aren’t thinking animals. “They don’t ‘care’ about how sick they make people, as long as they can spread,” Miller said.

With SARS-CoV-2, people can spread the virus quite efficiently already, even if they aren’t yet showing symptoms or never do, meaning “it’s not clear that there’s much pressure on the virus to cause less severe illness,” he said.

Overall, SARS-CoV-2 already causes fairly mild symptoms in most, though not for the elderly or those with chronic health problems, “and when there are high caseloads, the number of severe illnesses increases,” Miller said.

Advertisement

Article content

It will take weeks before scientists get a firm handle on how Omicron compares to Delta in terms of severity of disease, he and others said.

South Africa also has a high background of immunity: Studies suggest 40 to 50 per cent of South Africans were exposed to SARS-CoV-2 in earlier waves. One paper estimated that the number of infections was likely 7.8-fold higher than recorded cases. That immunity, combined with vaccination, could be providing protection against serious disease, which could help explain why Omicron infections so far appear milder.

What concerns scientists is that Omicron has a surprising number of mutations on the spike protein adorning the surface of SARS-Cov-2, especially the part that the virus uses to glob onto the cells in our bodies and that authorized vaccines target. Three changes in particular each make the spike better able to bind to our cells, more magnetic. “We’ve seen some of these three mutations in different variants of concern,” Otto said, but none before Omicron have all three. “When my colleagues saw that they were like, ‘Uh, oh.’”

Advertisement

Article content

Seven cases of Omicron had been confirmed in Canada as of Wednesday. Cases have been reported in Belgium, the Netherlands, France, Germany, Portugal and Italy and the United Kingdom.

At this point I give it about a 50-50 chance of being more or less severe. That’s how unsure science is at the moment

It’s not clear where or when Omicron first separated off from other SARS-CoV-2 variants, but it may date back to 2020. “It could be in a population that was so isolated that Omicron evolved there and it never got out until now,” said Otto, a professor in UBC’s department of zoology.

It may also have been living within one or two immunocompromised people unable to clear the virus. SARS-CoV-2 can reproduce to high loads, or linger much longer, in people with immune systems weakened by malnutrition, unclean drinking water, untreated HIV and other conditions, Miller said. And the longer the virus hangs around in the body the more opportunities to accumulate mutations.

Advertisement

Article content

“It’s possible that Omicron has been hiding out for most of 2021 inside somebody,” Otto said. “That would suggest that all these changes in the spike that we’re seeing actually weren’t selected to help transmit from person to person,” she said. “They were selected to survive and propagate within that person’s body.”

And if that’s the case, it’s possible Omicron selected to be less severe, “so that it didn’t kill that individual, and that individual was able to move around and eventually infect somebody else,” Otto said.

“But we really have zero idea. At this point I give it about a 50-50 chance of being more or less severe. That’s how unsure science is at the moment.”

While Omicron has a jumble of mutations in the spike protein, “there’s still a lot of spike that’s not changed, and our immune reactions should recognize other parts well if we’ve been vaccinated,” Otto said. “But it will spread like wildfire among the unvaccinated.”

Advertisement

Article content

While Moderna’s chief told the Financial Times this week he’s anticipating a “material drop” in vaccine efficacy, Otto is more optimistic. With a high vaccination rate, “we’ve got a base of immunity, and it’s not like (Omicron) has changed at hundreds of sites in the spike. It’s just changed at 30.” In the South African city of Tshwane, where Omicron was first detected, 87 per cent of hospital admissions are among the unvaccinated, The Guardian reported.

University of Manitoba’s Jason Kindrachuk: “We’re all trying to figure out very quickly what this is.”
University of Manitoba’s Jason Kindrachuk: “We’re all trying to figure out very quickly what this is.” Photo by Supplied

What Otto does find unnerving is that a fully vaccinated traveller who arrived in Hong Kong from Vancouver contracted the variant virus from another traveller from South Africa who was staying across the hall in the same airport quarantine hotel.

Though just one case, it could mean that Omicron is better able to transmit through smaller particles in the air, which would mean more longer-distance aerosol transmission, Otto said.

Advertisement

Article content

If it can spread much more easily through the air, “and you need even smaller particles to get infected because it’s so good at getting inside our body, that is a game changer,” Otto said. “That’s my nightmare.”

Jason Kindrachuk is already losing sleep. “The last five days have been just chaos,” said Kindrachuk, a member of Canada’s coronavirus variants rapid response network. “We’re all trying to figure out very quickly what this is.”

Even if Omicron does cause milder infections, “the question is, how much milder would it have to be for us to be more comfortable,” asked Kindrachuk, Canada Research Chair in the molecular pathogenesis of emerging and re-emerging viruses at the University of Manitoba.

And even though Omicron does appear to have some transmission advantage, is it able to out-compete Delta, or is it going to fizzle out? “We don’t know,” Kindrachuk said. “Right now we don’t have any conclusive data to say anything.”

But while the focus is suddenly on Omicron, “we still have Delta circulating widely across the globe and making a lot of people sick and still causing a lot of fatalities,” Kindrachuck said. “We can’t lose sight of the situation we are already in.”

• Email: [email protected] | Twitter:

Advertisement

Comments

Postmedia is committed to maintaining a lively but civil forum for discussion and encourage all readers to share their views on our articles. Comments may take up to an hour for moderation before appearing on the site. We ask you to keep your comments relevant and respectful. We have enabled email notifications—you will now receive an email if you receive a reply to your comment, there is an update to a comment thread you follow or if a user you follow comments. Visit our Community Guidelines for more information and details on how to adjust your email settings.

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