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Omicron thrives in airways, not lungs; new data on asymptomatic cases – Financial Post

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The following is a summary of some recent studies on COVID-19. They include research that warrants further study to corroborate the findings and that has yet to be certified by peer review.

Omicron multiplies faster in airways, slower in lungs

Major differences in how efficiently Omicron and other variants of the coronavirus multiply may help predict Omicron’s effects, researchers said on Wednesday.

Compared to the earlier Delta variant, Omicron multiplies itself 70 times more quickly in tissues that line airway passages, which may facilitate person-to-person spread, they said. But in lung tissues, Omicron replicates 10 times more slowly than the original version of the coronavirus, which might contribute to less-severe illness.

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A formal report of the findings is under peer review for publication and has not been released by the research team. In a news release https://www.med.hku.hk/en/news/press/20211215-omicron-sars-cov-2-infection issued by Hong Kong University, study leader Dr. Michael Chan Chi-wai said, “It is important to note that the severity of disease in humans is not determined only by virus replication” but also by each person’s immune response to the infection, which sometimes evolves into life-threatening inflammation.

Chan added, “By infecting many more people, a very infectious virus may cause more severe disease and death even though the virus itself may be less pathogenic. Therefore, taken together with our recent studies showing that the Omicron variant can partially escape immunity from vaccines and past infection, the overall threat from Omicron variant is likely to be very significant.”

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Omicron grips cells more tightly, withstands some antibodies

A structural model of how the Omicron variant attaches to cells and antibodies sheds light on its behavior and will help in designing neutralizing antibodies, according to researchers.

Using computer models of the spike protein on Omicron’s surface, they analyzed molecular interactions occurring when the spike grabs onto a cell-surface protein called ACE2, the virus’s gateway into the cell.

Metaphorically, the original virus had a handshake with ACE2, but Omicron’s grip “looks more like a couple holding hands with their fingers entwined,” said Joseph Lubin of Rutgers University in New Jersey. The “molecular anatomy” of the grip may assist in explaining how Omicron’s mutations cooperate to help it infect cells, Lubin added.

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The research team also modeled the spike with different classes of antibodies trying to attack it. The antibodies attack from different angles, “like a football team’s defense might tackle a ball carrier,” with one person grabbing from behind, another from the front, Lubin said. Some antibodies “appear likely to get shaken off” while others are likely to remain effective. Booster vaccines raise antibody levels, resulting in “more defenders,” which might compensate to some extent for “a weaker grip of an individual antibody,” Lubin said.

The findings, posted on Monday on the website bioRxiv https://www.biorxiv.org/content/10.1101/2021.12.12.472313v1 ahead of peer review, need to be verified, “particularly with real-world samples from people,” Lubin said. “While our molecular structure predictions are by no means a final word on Omicron, (we hope) they enable a faster and more effective response from the global community.”

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Four in 10 infected people may unknowingly spread virus

Infected people who show no symptoms might be contributing significantly to transmission of SARS-CoV-2, the virus that causes COVID-19, given that they account for 40.5% of confirmed infections worldwide, according to a study published online Tuesday in the journal JAMA Network Open https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2787098.

The researchers pooled data from 77 earlier studies involving a total of 19,884 individuals with confirmed SARS-CoV-2 infections. They found that among infected people in the general community, about 40% were asymptomatic, as were 54% of infected pregnant women, 53% of infected air or cruise travelers, 48% of infected nursing home residents or staff and 30% of infected healthcare workers or hospitalized patients.

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The pooled percentage of asymptomatic infections was about 46% in North America, 44% in Europe and 28% in Asia.

“The high percentage of asymptomatic infections highlights the potential transmission risk of asymptomatic infections in communities,” wrote Min Liu and colleagues at Peking University in China. Officials should screen for asymptomatic infections, and those who are identified “should be under management similar to that for confirmed infections, including isolating and contact tracing.”

Click for a Reuters graphic https://tmsnrt.rs/3c7R3Bl on vaccines in development.

(Reporting by Nancy Lapid; Editing by Will Dunham)

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'Very nice spring, very nice summer': Omicron will bring us closer to normal, experts say – National Post

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‘We need to lay out a strategy and a plan towards moving back toward something that is nearer normality’

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Anna Bershteyn says there are absolutely no guarantees, of course, but if asked to read the tea leaves, she sees “a very nice spring, a very nice summer, where people can let loose,” see others and not worry so much about COVID-19 .

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It’s just a hope, “but if I had to make a guess, I would say that what Omicron will probably give us is a period of respite,” said Bershteyn, an assistant professor in the department of population health at New York University Grossman School of Medicine. Immunity gained through vaccination, infection or a combination of the two, could move populations closer to controllable levels of COVID, she and other scientists said. The hope is that the virus “sort of vaccinates itself” — that a milder strain gives us immunity to a later, potentially more severe one.

While hospital and ICU numbers are rising nationally, Omicron infections may have peaked and the country could be on a downward slope, federal health officials said Friday.

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COVID is here to stay. SARS-CoV-2 will continue to live in the human population, Dr. Theresa Tam, Canada’s chief public health officer said. While we must prepare for more potential unusual variants, “we do need to lay out a strategy and a plan towards moving back toward something that is nearer normality,” Tam said . In England, mandatory masking in public spaces and vaccine passports will be dropped beginning next week, while Spain is moving toward treating SARS-CoV-2 much like seasonal flu.

Many questions linger: It’s not clear how long immunity to Omicron will last, whether we could see a second wave, or whether infection with a milder stain will indeed provide immunity against whichever Greek letter-named version of SARS-CoV-2 comes next. The virus has already proven whip smart — scientists didn’t see heavily mutated Omicron coming — and it’s still evolving.

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“The big game changer is indeed the moment when nearly everybody will have had some sort of immunity,” Dr. Peter Juni, of Ontario’s COVID-19 science table  recently told a COVID research consortium . “I can’t guarantee endemicity relatively soon, but I can guarantee we can move much closer to endemicity after the Omicron wave.”

Here’s what we know about where we are now and where we need to go.

Rapid rise, rapid descent?

“Our modelling suggests that we are at the peak around now, with some provinces (Ontario and Quebec, which experienced Omicron earliest) just past the peak and others just behind it,” said Caroline Colijn, an associate professor of mathematics at Simon Fraser University and COVID-19 modeller.

In Ontario, the rate of hospitalizations and intensive care admissions is slowing. Restaurants and gyms will reopen starting Jan. 31, with all remaining restrictions to go by mid-March, Premier Doug Ford announced Wednesday. British Columbia is seeing a slowing in transmission rate. “That’s partly the end of the holidays, but I think it partly is  a lot  of people have COVID right now,” said Colijn and that’s having a dampening effect. More people are isolating “or cancelling things if they hear five of their friends have COVID.” That, combined with a shorter course of infections, can drive a speedy decline, she said.

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Our modelling suggests that we are at the peak around now

But Canada might also have a more rounded peak, or double peaks, because of the timing with schools and universities reopening and the lifting of restrictions, Colijn said. “We may not see the very rapid decline that has been seen in South Africa, for example.”

Official case counts are almost irrelevant, with testing systems so overwhelmed. “But it’s important if the number of actual infections happening starts to go down quickly, because that’s going to decrease the burden on everybody — fewer people sick, fewer people in hospital, fewer workplace closures, fewer schools affected,” Colijn said.

Why not just get infected and get it over with?

Famed cardiologist and author Dr. Eric Topol isn’t thrilled with the “Omicron will ultimately find just about everybody,” messaging. “Let’s not invite an unpredictable virus that can cause long COVID,” or secondary attacks, where people who may not be particularly at risk of a bad infection themselves unwittingly pass the virus to someone who can wind up very sick,” Topol said, during a recent University of California, San Francisco Department of Medicine Grand Rounds Q&A. 

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In Australia, “COVID chasers” are hoping to time infections when it’s less inconvenient to isolate. Their thinking runs the lines of, “It’s going to happen anyway, I want to live my life, I’m sick of trying to avoid COVID and it’s likely to be mild in someone like me.”

It’s not a terribly brilliant idea, Topol, founder and director of Scripps Research Translational Institute, and other scientists said. Omicron can cause severe disease. It’s not uniformly mild. With hospitals grappling with shortages of staff and COVID-19 drugs, people who do end up in hospital risk ending up with less-than-optimal care, Juni said. And while it will take months before it’s known whether Omicron can cause long COVID, the phenomenon typically follows mild infections.

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  1. FILE PHOTO: A respiratory therapist and six nurses prone a coronavirus disease (COVID-19) patient inside the intensive care unit of Humber River Hospital in Toronto, Ontario, Canada April 19, 2021.

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Vaccines are still the best shot at making COVID manageable

The vaccines are still holding their own against severe disease with Omicron, and a third dose boosts immunity even higher. Still, demand for third doses appears to be slowing, and while Pfizer has said it should have a vaccine that targets Omicron specifically by March, Topol and others said what’s needed is a universal, “pan” coronavirus vaccine that would protect against all variants and make it harder for the virus to mutate its way around. Omicron proved that SARS-CoV-2 can take huge leaps in evolution, “and get all these mutations all in one jump,” Bershteyn said. “You really can’t place Omicron on the family tree of variants that we’ve seen before. It sort of came out of nowhere, and as far as I can tell there’s no biological rule that says that it couldn’t do this again  and  be very contagious and very deadly at the same time.”

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“The unvaccinated who do not have a boost to their immunity from vaccine are likely to become susceptible again to whatever variant comes next,” she said, and regulatory discussions should be happening now, including, would manufacturers have to do a full clinical trial of a new vaccine, or a small, short trial, looking at the antibody response? How long to monitor for safety? A vaccine against Omicron is three months away. If a more dangerous variant emerged, “we couldn’t wait three months. You’d have to completely lock down everything. It’s just not feasible.”

What’s the endgame?

“Waning immunity and the emergence of new variants will shape the long-term burden and dynamics of COVID-19,” Colijn and colleagues wrote in a pre-print.

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“If we can get another infection in a couple of months, that’s not a good thing for where this virus settles out,” Colijn said. “But if we’re well protected for a year, that’s pretty good news. And what that means is that (COVID) will decline to hopefully pretty low levels and stay at those levels.”

But endemic doesn’t mean “not a problem,” she said. “It just means that it’s stable — it’s not having this huge wave that goes through the population.”

Waning immunity and the emergence of new variants will shape the long-term burden and dynamics of COVID-19

She doesn’t think there’s pressure on the virus to get more severe. Transmission is where the virus is having “its reproductive opportunities. We have the high transmissibility without it carrying along a really high severity. So, hopefully, we don’t get the big, bad new variant,” Colijn said.

Hospitalizations will never be reduced to zero. “There are always going to be frail vulnerable people who succumb to this virus,” McMaster University infectious diseases specialist Dr. Martha Fulford said in an earlier interview. Once past this hump, and with more protection because of boosters, more immunity from infections and more effective treatments, a broader conversation will be needed about the risks posed by COVID and the risks that exist from locking down “forever and a day,” she said.

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Change to shorter isolation period part of managing COVID 19 in B.C.: top doctor – Vancouver Sun

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Dr. Bonnie Henry says unvaccinated adults who test positive are at risk of having longer-lasting and more severe illness and must isolate for 10 days but those who are vaccinated should isolate for five days.

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VANCOUVER — British Columbia’s top doctor says the current wave of COVID-19 is causing less severe illness and that calls for a shift to shorter periods of isolation in order to minimize societal disruptions.

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Dr. Bonnie Henry says unvaccinated adults who test positive are at risk of having longer-lasting and more severe illness and must isolate for 10 days but those who are vaccinated should isolate for five days.

She says children are at much lower risk of severe illness and are able to clear an infection faster, so five days’ isolation is also suitable for them, with mounting evidence showing they need to interact with others as part of their social development.

Henry says testing is not needed for most people who have symptoms and are likely to have a mild illness but those who are immunocompromised and over 70 could end up with more serious illness and likely need a test.

She says vaccination remains the best protection for everyone, especially for vulnerable groups, but anyone with symptoms should stay home until they feel better, the same as with other respiratory illnesses like the flu.

Henry says COVID-19 is far from being an endemic illness so restrictions that are in place are needed to prevent more hospitalizations, though those numbers have been declining.

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Canada’s Omicron wave may have peaked; hospitals still under strain

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Canada is seeing early signs that a wave of infections caused by the Omicron variant of COVID-19 may have peaked, but hospitals are still under intense strain, chief public health officer Theresa Tam said on Friday.

Tam made her remarks days after the provinces of Ontario and Quebec – which together account for around 61% of Canada’s population of 38.5 million – said they were more optimistic about their ability to deal with coronavirus infections.

“There are early indications that infections may have peaked at the national level,” Tam said, noting daily case counts had dropped 28% compared to the previous week.

“However, daily hospital and intensive care unit numbers are still rising steeply, and many hospitals across Canada are under intense strain,” she said in a news briefing.

Over the past week, an average of more than 10,000 people with COVID-19 were being treated in hospitals every day, surpassing peak daily numbers for all previous waves, she said.

Although politicians at all levels have repeatedly urged Canadians to get inoculated against the virus, Tam said 6.5 million people in the country were still not fully vaccinated.

(Reporting by David Ljunggren in Ottawa and Ismail Shakil in BengaluruEditing by Paul Simao)

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