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How does Omicron spread so fast? Virus may now be multiplying 70 times quicker in airways – CBC News



New research from a team in Hong Kong offers a clue to why the Omicron coronavirus variant is spreading so astonishingly fast around the world: it may be multiplying 70 times quicker than earlier strains within our lower airways.

The laboratory-based study, led by researchers from the LKS Faculty of Medicine at the University of Hong Kong, was shared online as a press release on Wednesday and is currently undergoing peer review for publication.

The researchers found that, just 24 hours after infection, Omicron multiplies 70 times faster than either the Delta variant or the original SARS-CoV-2 virus within tissue samples of human bronchi — the two large tubes that carry air from your windpipe to your lungs.

It’s a finding that could explain why Omicron seems to transmit faster between humans than previous variants, and offers a striking contrast to how the variant replicated in the research team’s samples of actual lung tissue compared to the bronchi. Within those lung samples, the variant multiplied at a rate more than 10 times slower than the original virus.

It’s the lungs — not the bronchi — that are linked to potentially life-threatening COVID-19 complications such as pneumonia and, in severe cases, acute respiratory distress syndrome or ARDS. So if these findings hold up in a real-world setting, the team suspects that slower replication in the lungs might mean reduced severity of disease.

The finding also echoes early evidence from South Africa suggesting Omicron may be linked to a milder course of illness.

But severity of disease is not only a function of where and how quickly a virus replicates in a certain organ, “it is also a function of our immune response,” said Dr. Dominik Mertz, an infectious diseases specialist with Hamilton’s McMaster University, in an email exchange with CBC News.

People need to be careful in drawing direct conclusions from lab-based studies compared to how infections will actually present in the real world, he wrote.

“The latter must be based on observations in those who have confirmed infections, and we still have to learn more in terms of actual severity in a population like ours which has first and foremost mRNA-vaccine immunity.”

Omicron cases have been identified in more than 70 countries around the world, including Canada, where the variant is expected to take over. (Evan Mitsui/CBC)

Omicron threat likely ‘very significant’

The lead researcher from Hong Kong — Dr. Michael Chan Chi-wai, an associate professor of the university’s school of public health — also acknowledged that disease severity is tied to other factors, like whether someone’s immune system goes haywire in response to a coronavirus infection in what’s known as a “cytokine storm.”

“It is also noted that, 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,” he said in a statement. 

“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 [the] Omicron variant is likely to be very significant.”

Ryan Troyer, a virologist and researcher at Western University in London, Ont., stressed that the Hong Kong team’s results are still preliminary.

“The differences they’re finding here look fairly significant,” he said. “It’ll be interesting to see if this is backed up by additional studies.”

Electron micrograph of the human bronchus tissues after infection with SARS-CoV-2. Red arrows show viral particles. (Supplied by the LKS Faculty of Medicine at The University of Hong Kong.)

Variety of symptoms, from mild to severe

Troyer also noted that the study adds to the growing pile of evidence that COVID-19 infections may present in a variety of ways, even before the rise of the Omicron variant, with symptoms ranging from severe and life-threatening to far milder and perhaps barely-noticeable.

Take the ongoing testing of professional sports teams like the NBA and NHL, for instance. Troyer said those tests often pick up infections among the young, healthy players that the athletes themselves didn’t even notice — since vaccination status, the age of those infected, and other factors all play a role in disease severity. 

A Tuesday presentation from Discovery Health, South Africa’s largest private health insurance administrator, offered an analysis of an Omicron outbreak using more than 200,000 COVID-19 test results.

The team noted that for patients with Omicron who needed acute care outside of a hospital setting, the incubation period is typically only three to four days, with patients recovering a few days after that — a tighter timeframe than the previous estimated incubation period ranging from one to 14 days.

WATCH | How boosters protect against Omicron:

How boosters protect against Omicron

17 hours ago

Duration 1:35

Dr. Joss Reimer explains how boosters will help fight against Omicron and answers other questions about immunity. 1:35

“The most common early symptom seems to be a scratchy or sore throat,” said Dr. Ryan Noach, CEO of Discovery Health, during the presentation.

Nasal congestion and dry cough are also commonly reported, he continued, along with muscle aches or pain manifesting in different areas. “Particularly in lower back pain, which seems to be a hallmark in the out-of-hospital presentation,” he said.

Such run-of-the-mill symptoms are easy to disregard, but experts say that’s one of the many ways a more-transmissible variant might be spreading — both quickly and quietly.

“I think it’s important for people to think about the fact that you can’t assume that lack of symptoms means lack of virus,” Troyer said.

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Ontario to start lifting COVID-related curbs, Quebec more cautious



Canada’s most populous province of Ontario has blunted transmission of the Omicron coronavirus variant and will gradually ease restrictions on businesses from end-January, Premier Doug Ford said on Thursday.

The health care system is starting to stabilize in the wake of limitations imposed on Jan. 5, Ford told a news conference, saying Omicron cases should peak later this month.

“We can be confident that the worst is behind us and that we are now in a position to cautiously and gradually ease public health measures,” Ford said.

The province will allow restaurants, malls, and cinemas to operate with a 50% capacity limit from Jan. 31, before removing more curbs in February and March.

“While February will continue to present its own challenges, given current trends these are challenges we are confident we can manage,” Ford said.

In neighbouring Quebec, premier Francois Legault said he would maintain restrictions to help protect the health care system even though Omicron cases had peaked.

“I understand we are all tired, but lives are at stake. I’m currently under a lot of pressure to remove measures, but my duty is to be responsible to protect the lives of Quebecers,” he told a news conference.

Ontario and Quebec together account for around 61% of Canada’s population of 38.2 million people.


(Reporting by Ismail Shakil in Bengaluru and David Ljunggren in Ottawa; Editing by Tomasz Janowski and Grant McCool)

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Canadian vaccine mandate to lead to inflation, empty shelves, trucking executives say



Canadian consumers should soon see higher prices and some empty shelves in supermarkets and other retail outlets because of disruptions stemming from a COVID-19 vaccine mandate for cross-border truckers, top trucking executives warned this week.

The mandate, imposed by Ottawa to help curb the spread of the virus, has cost six Canadian trucking companies about 10% of their international drivers, and many are hiking wages to lure new operators during what they said is the worst labor shortage they have experienced.

Within the next two weeks, consumers will see “there’s not as many choices on the shelves,” said Dan Einwechter, chairman and chief executive officer of Challenger Motor Freight Inc in Cambridge, Ontario.

“Eventually the prices will be passed on from the sellers of those products, because we’re passing on our increases to them,” he said.

Canada’s inflation rate hit a 30-year high of 4.8% in December and economists said the vaccine mandate may contribute to keeping prices higher for longer. In the United States, inflation surged 7% on a year-on-year basis in December, the largest rise in nearly four decades.

Prime Minister Justin Trudeau, who has championed vaccine requirements for federal employees, has resisted pressure from industry to delay or drop the mandate that was announced in November.

The vaccine requirement to enter Canada started on Jan. 15, and the one to enter the United States begins on Saturday.

Since more than two-thirds of the C$650 billion ($521 billion) in goods traded annually between Canada and the United States travels on roads, truckers were deemed essential workers until now and traveled freely even when the border was closed for 20 months.

Trudeau defended the mandate on Wednesday, saying Canada was “aligned” with the United States, its largest trading partner.

“We will continue to make sure that we are getting what we need in Canada while, as always, putting the safety and health of Canadians as our top priority,” Trudeau said.

As many as 32,000, or 20%, of the 160,000 Canadian and American cross-border truck drivers may be taken off the roads by the mandate, the Canadian Trucking Alliance (CTA) estimates. The industry was short some 18,000 drivers even before the mandate, CTA said.

“We raised our base rate for cross-border drivers effective Jan. 1 by almost 20% … and it didn’t gain us any drivers,” said Rob Penner, president and CEO of Winnipeg, Manitoba-based Bison Transport. “There’s more freight than there is people right now.”

Canada’s transport ministry said in a statement the measure was not negatively affecting the supply of goods, while cross-border truck traffic had not varied significantly since the mandate came into effect.


The six executives who manage nearly 9,200 trucks between their companies and have a combined 173 years in the industry say strong demand for freight during a labor shortage will inevitably translate into higher prices for consumers.

“We’ve been oversold by 5% or 10%, depending on the day, for the last four or five months … The timing of all this couldn’t have been worse,” said Mark Seymour, CEO of Kriska Transportation Group in Prescott, Ontario.

Canadian firms see labor shortages intensifying and wage pressures increasing, according to a Bank of Canada survey released on Monday. Investors increasingly expect the central bank to raise interest rates next week for the first time since 2018.

Fresh foods are particularly sensitive to freight problems because they expire rapidly, though all imports from the United States could be affected, the trucking managers said.

“We have to move the milk, we have to move food. But the rates are going to be much higher,” said Doug Sutherland, president of Sutherland Group Enterprises in Salmo, British Columbia.

“Inflation is going to be the biggest impact of what’s going on here.”

($1 = 1.2478 Canadian dollars)

(Reporting by Steve Scherer; Additional reporting by David Ljunggren; Editing by Paul Simao)

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Natural immunity against COVID lowered risk more than vaccines against Delta variant, new study says – Euronews



Unvaccinated people who had previously contracted COVID-19 were better protected against the Delta variant than those who were only vaccinated, a new study published on Wednesday by a US health authority said.

Despite this, “vaccination remains the safest strategy” against the disease, the Centers for Disease Control and Prevention (CDC) said when publishing the data.

It also pointed out that contracting the disease exposes you to serious complications, while vaccines have proven to be extremely safe and effective.

The study was conducted before booster doses were widely available, and before the emergence of the Omicron variant, which now accounts for more than 99 per cent of new cases in the US. It is therefore possible that the balance has shifted towards vaccination being more effective than immunity following infection.

However, the results published on Wednesday provide key insights into the differences between vaccine-acquired and post-infection immunity.

The health authorities studied cases in the states of New York and California from late May to November 2021. Delta became the majority disease in the US at the end of June.

During the entire period under analysis, the people with the least protection by far were those who had neither been vaccinated nor fallen ill in the past.

But before Delta, vaccinated people who had never contracted COVID-19 were better protected than unvaccinated people who had already fallen ill.

After the introduction of Delta, the ratio was reversed.

Less risk to infected but not vaccinated people

The study analysed the risk of getting Delta compared to the risk of those most likely to get it, in other words, people who had neither been vaccinated nor infected in the past by the beginning of October.

Those that had been vaccinated but never infected with COVID-19 were six times less likely to get it in California, and about five times less likely in New York.

But the risk was even lower for previously infected but not vaccinated individuals: by 29 in California, and by 15 in New York.

When analysing the risk of hospitalisation, this time in California only, the researchers found a similar reversal between the two periods.

“This could be due to different immune response stimuli” caused either by encountering the real virus or a vaccine, the CDC explained.

The reversal also “coincided with the onset of vaccine-induced immunity decline in many people” before booster doses, the study authors added.

The CDC noted too that work on Delta in other countries “has also demonstrated increased protection of previously infected individuals, both vaccinated and unvaccinated, compared with vaccination alone”.

They emphasised that further studies were needed to investigate the durability of protection conferred by infection with each of the variants, including Omicron.

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