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Why the delta variant is spreading COVID-19 so quickly — and what that means for Canada – CBC.ca

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It’s the word on everyone’s mind right now when it comes to the COVID-19 pandemic: Delta.

The highly contagious variant, which was first discovered in India in late 2020, has spread around the world and now accounts for the majority of cases in Canada and various other countries. 

The recent spread in the United States has led the U.S. Centers for Disease Control and Prevention (CDC) to recommend that Americans wear masks in areas with substantial transmission “regardless of vaccination status.”

So, why is this particular variant spreading so rapidly? And what’s the mechanism at play behind its apparent success at infecting human hosts?

The answers are complicated, and there are still unknowns around how, exactly, the delta variant was able to take hold at such a brisk pace, throwing a wrench in global efforts to wind down the pandemic.

But we are getting closer to understanding how it works — and why vaccines, thankfully, still hold up.

How contagious is delta?

The delta variant is thought to be significantly more contagious than the early strain of SARS-CoV-2, the virus which first swept around the world. Delta has been dubbed a variant of concern by the World Health Organization (WHO).

“We are fighting the same virus but a virus that has become fitter and better adapted to transmitting amongst us humans,” said Dr. Michael Ryan, executive director of the WHO’s health emergencies program, during a Friday briefing.

Scientists estimate it’s spreading roughly 50 per cent faster than the alpha variant, which was 50 per cent more contagious than the original virus strain, according to the Yale School of Public Health.

That means every person infected is capable of passing the virus on to more people than before, helping this variant spread through populations quickly — and even faster among those whose immune systems aren’t already on high alert due to a previous COVID-19 infection or vaccination.

WATCH | COVID-19 delta variant a ‘dangerous virus,’ warns WHO:

The World Health Organization says the trajectory for the COVID-19 delta variant in some countries is almost ‘vertical’ and warns that even partially vaccinated countries are at great risk because of its high transmissibility. (Willy Kurniawan/Reuters) 0:56

Why is it more transmissible?

While the exact mechanism making delta more transmissible isn’t entirely clear, emerging research is hinting at possible reasons why it’s so infectious.

One lab-based study published in the journal Cell Host & Microbe, from researchers at the Kumamoto University and Weizmann Institute of Science, suggests mutations on the spike protein of this SARS-CoV-2 variant can evade cellular immunity and may increase its infectivity. 

The spike protein is a crucial feature on the surface of the coronavirus that allows it to gain access to our cells, explained University of Ottawa epidemiologist Raywat Deonandan. 

“It fits into a receptor on our cells and then it enters the cell via that receptor. Something about the mutation has changed the shape or a feature on the spike protein that makes it fit a bit better,” he said.

“As a result, you need fewer viruses present to achieve infection.”

People wear masks while walking in Grand Central Terminal in New York City on July 27. Due to the rapidly spreading delta variant, the U.S. Centers for Disease Control and Prevention now recommends that fully vaccinated people begin wearing masks indoors again in places with high COVID-19 transmission rates. (Spencer Platt/Getty Images)

Another study from a team in China, which has not yet been peer-reviewed, found people infected with the delta variant carried, on average, a more than 1,000 times higher amount of virus in their nose compared to the original strain — which likely means they’re shedding more of it.

The researchers also found people carrying this variant test positive faster: around four days after exposure, compared to around six for the original strain. That suggests delta replicates at a quicker pace inside someone’s body.

“You may actually excrete more virus and that’s why it’s more transmissible,” microbiologist Sharon Peacock, who runs the U.K.’s efforts to sequence the genomes of coronavirus variants, recently told Reuters.

How well do vaccines protect against it?

If carrying around delta means people may be shedding more of the virus and transmitting it to others more easily, vaccines definitely have a tougher task — since people’s immune systems are now facing a larger army and need to ramp up to mount a defence.

In the U.S., the CDC warned Friday that emerging data from a county in Massachusetts suggests the higher viral loads could mean vaccinated people can still transmit delta to others.

But the good news is that leading vaccines, including those approved for use in Canada, do seem to ward off serious disease that can lead to hospitalization or death.

A recent study in the New England Journal of Medicine found two doses of the Pfizer-BioNTech vaccine were 88 per cent effective against the delta variant, while two shots of the AstraZeneca-Oxford vaccine were 67 per cent effective. 

It marked a drop in the vaccines’ ability to curb infections of any severity level — whether mild or more severe — when compared to the earlier alpha variant, but the researchers said there were only “modest differences.”

Health-care providers administer the Pfizer-BioNTech COVID-19 vaccine at a pop-up clinic in Toronto on July 27. Leading vaccines do seem to ward off serious disease that can lead to hospitalization or death, even against the delta variant. (Evan Mitsui/CBC)

Recent data from Israel also shows the Pfizer shot reduced the risk of severe disease by a whopping 91 per cent, and hospitalization by 88 per cent. The level of protection against symptomatic infections in general was less than half that, but there are questions about how the government collected its data and how many infections were involved.

Still, it’s a hopeful real-world snapshot of how a leading mRNA vaccine is warding off serious illness, and it is likely the highly similar Moderna shot also being used in Canada would fare similarly.

“I don’t want to minimize the risk of things like ‘long COVID,’ but one of the biggest risks is how likely you’ll develop serious disease after being infected,” stressed Angela Rasmussen, a virologist with the University of Saskatchewan’s Vaccine and Infectious Disease Organization.

“The bottom line there,” she said, “is vaccination is still very protective.”

How widespread is delta?

This variant has definitely taken hold around the world since being first reported in October 2020 in India, with other countries later reporting high levels as well.

“It’s out-competing all other viruses, because it just spreads so much more efficiently,” virologist Shane Crotty, of the La Jolla Institute for Immunology in San Diego, told Reuters.

In the U.S., delta now represents more than 80 per cent of new infections. Cases are spiking in many areas with low vaccination rates, and data shows unvaccinated individuals total nearly 97 per cent of all severe cases.

Across Africa, meagre vaccination rates, coupled with the rise of the delta variant, are putting major pressure on various countries’ hospital systems.

The variant is now being found in at least 26 African nations, and 21 countries have seen cases rise by more than 20 per cent for at least two weeks running, the WHO announced in late July.



Countries from the U.K. to Singapore are also dealing with delta surges — including Canada. Variants of this virus now make up the bulk of our SARS-CoV-2 infections.

By early July, delta made up roughly 70 per cent of the country’s cases, according to the latest available whole genome sequencing data from the Public Health Agency of Canada.

That marked a massive jump from early May, when delta still represented less than 10 per cent of sequenced infections.

So what does this all mean for Canada?

There are now growing signs that the rise of delta could spark another overall surge in cases — even though nearly six in 10 Canadians are now fully vaccinated, millions still remain unprotected.

Ontario and Quebec have largely plateaued for new daily COVID-19 cases after weeks of falling numbers, while the number of new cases reported each day in B.C. has actually tripled during the last three weeks.

The virus is also spreading faster in Alberta than it did during the peak of the province’s third wave — all while that province is set to loosen its tightest restrictions around mask-wearing and isolation requirements.

WATCH | Alberta removing most COVID-19 isolation, testing requirements:

Alberta will be pulling back on requirements for COVID-19 testing, contact tracing and quarantines, despite rising cases in the province. 2:05

Even if overall case growth starts to spike, some experts are hopeful Canada, as a whole, will avoid the most dire outcomes, including overwhelming pressure on the country’s hospital networks and a death toll similar to earlier waves. 

Most people may still be able to avoid getting infected if they’re both vaccinated and playing it safe, even in high-density, urban areas, Rasmussen said, though she does expect school outbreaks if mitigation measures aren’t in place.

Many Canadians are still wearing masks and taking precautions in social settings, said Deonandan.

“I’m fairly optimistic that if this good decision-making continues, we could be world leaders in this endeavour.”

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Health Canada approves updated Moderna COVID-19 vaccine

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TORONTO – Health Canada has authorized Moderna’s updated COVID-19 vaccine that protects against currently circulating variants of the virus.

The mRNA vaccine, called Spikevax, has been reformulated to target the KP.2 subvariant of Omicron.

It will replace the previous version of the vaccine that was released a year ago, which targeted the XBB.1.5 subvariant of Omicron.

Health Canada recently asked provinces and territories to get rid of their older COVID-19 vaccines to ensure the most current vaccine will be used during this fall’s respiratory virus season.

Health Canada is also reviewing two other updated COVID-19 vaccines but has not yet authorized them.

They are Pfizer’s Comirnaty, which is also an mRNA vaccine, as well as Novavax’s protein-based vaccine.

This report by The Canadian Press was first published Sept. 17, 2024.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

The Canadian Press. All rights reserved.

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These people say they got listeria after drinking recalled plant-based milks

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TORONTO – Sanniah Jabeen holds a sonogram of the unborn baby she lost after contracting listeria last December. Beneath, it says “love at first sight.”

Jabeen says she believes she and her baby were poisoned by a listeria outbreak linked to some plant-based milks and wants answers. An investigation continues into the recall declared July 8 of several Silk and Great Value plant-based beverages.

“I don’t even have the words. I’m still processing that,” Jabeen says of her loss. She was 18 weeks pregnant when she went into preterm labour.

The first infection linked to the recall was traced back to August 2023. One year later on Aug. 12, 2024, the Public Health Agency of Canada said three people had died and 20 were infected.

The number of cases is likely much higher, says Lawrence Goodridge, Canada Research Chair in foodborne pathogen dynamics at the University of Guelph: “For every person known, generally speaking, there’s typically 20 to 25 or maybe 30 people that are unknown.”

The case count has remained unchanged over the last month, but the Public Health Agency of Canada says it won’t declare the outbreak over until early October because of listeria’s 70-day incubation period and the reporting delays that accompany it.

Danone Canada’s head of communications said in an email Wednesday that the company is still investigating the “root cause” of the outbreak, which has been linked to a production line at a Pickering, Ont., packaging facility.

Pregnant people, adults over 60, and those with weakened immune systems are most at risk of becoming sick with severe listeriosis. If the infection spreads to an unborn baby, Health Canada says it can cause miscarriage, stillbirth, premature birth or life-threatening illness in a newborn.

The Canadian Press spoke to 10 people, from the parents of a toddler to an 89-year-old senior, who say they became sick with listeria after drinking from cartons of plant-based milk stamped with the recalled product code. Here’s a look at some of their experiences.

Sanniah Jabeen, 32, Toronto

Jabeen says she regularly drank Silk oat and almond milk in smoothies while pregnant, and began vomiting seven times a day and shivering at night in December 2023. She had “the worst headache of (her) life” when she went to the emergency room on Dec. 15.

“I just wasn’t functioning like a normal human being,” Jabeen says.

Told she was dehydrated, Jabeen was given fluids and a blood test and sent home. Four days later, she returned to hospital.

“They told me that since you’re 18 weeks, there’s nothing you can do to save your baby,” says Jabeen, who moved to Toronto from Pakistan five years ago.

Jabeen later learned she had listeriosis and an autopsy revealed her baby was infected, too.

“It broke my heart to read that report because I was just imagining my baby drinking poisoned amniotic fluid inside of me. The womb is a place where your baby is supposed to be the safest,” Jabeen said.

Jabeen’s case is likely not included in PHAC’s count. Jabeen says she was called by Health Canada and asked what dairy and fresh produce she ate – foods more commonly associated with listeria – but not asked about plant-based beverages.

She’s pregnant again, and is due in several months. At first, she was scared to eat, not knowing what caused the infection during her last pregnancy.

“Ever since I learned about the almond, oat milk situation, I’ve been feeling a bit better knowing that it wasn’t something that I did. It was something else that caused it. It wasn’t my fault,” Jabeen said.

She’s since joined a proposed class action lawsuit launched by LPC Avocates against the manufacturers and sellers of Silk and Great Value plant-based beverages. The lawsuit has not yet been certified by a judge.

Natalie Grant and her seven year-old daughter, Bowmanville, Ont.

Natalie Grant says she was in a hospital waiting room when she saw a television news report about the recall. She wondered if the dark chocolate almond milk her daughter drank daily was contaminated.

She had brought the girl to hospital because she was vomiting every half hour, constantly on the toilet with diarrhea, and had severe pain in her abdomen.

“I’m definitely thinking that this is a pretty solid chance that she’s got listeria at this point because I knew she had all the symptoms,” Grant says of seeing the news report.

Once her daughter could hold fluids, they went home and Grant cross-checked the recalled product code – 7825 – with the one on her carton. They matched.

“I called the emerg and I said I’m pretty confident she’s been exposed,” Grant said. She was told to return to the hospital if her daughter’s symptoms worsened. An hour and a half later, her fever spiked, the vomiting returned, her face flushed and her energy plummeted.

Grant says they were sent to a hospital in Ajax, Ont. and stayed two weeks while her daughter received antibiotics four times a day until she was discharged July 23.

“Knowing that my little one was just so affected and how it affected us as a family alone, there’s a bitterness left behind,” Grant said. She’s also joined the proposed class action.

Thelma Feldman, 89, Toronto

Thelma Feldman says she regularly taught yoga to friends in her condo building before getting sickened by listeria on July 2. Now, she has a walker and her body aches. She has headaches and digestive problems.

“I’m kind of depressed,” she says.

“It’s caused me a lot of physical and emotional pain.”

Much of the early days of her illness are a blur. She knows she boarded an ambulance with profuse diarrhea on July 2 and spent five days at North York General Hospital. Afterwards, she remembers Health Canada officials entering her apartment and removing Silk almond milk from her fridge, and volunteers from a community organization giving her sponge baths.

“At my age, 89, I’m not a kid anymore and healing takes longer,” Feldman says.

“I don’t even feel like being with people. I just sit at home.”

Jasmine Jiles and three-year-old Max, Kahnawake Mohawk Territory, Que.

Jasmine Jiles says her three-year-old son Max came down with flu-like symptoms and cradled his ears in what she interpreted as a sign of pain, like the one pounding in her own head, around early July.

When Jiles heard about the recall soon after, she called Danone Canada, the plant-based milk manufacturer, to find out if their Silk coconut milk was in the contaminated batch. It was, she says.

“My son is very small, he’s very young, so I asked what we do in terms of overall monitoring and she said someone from the company would get in touch within 24 to 48 hours,” Jiles says from a First Nations reserve near Montreal.

“I never got a call back. I never got an email”

At home, her son’s fever broke after three days, but gas pains stuck with him, she says. It took a couple weeks for him to get back to normal.

“In hindsight, I should have taken him (to the hospital) but we just tried to see if we could nurse him at home because wait times are pretty extreme,” Jiles says, “and I don’t have child care at the moment.”

Joseph Desmond, 50, Sydney, N.S.

Joseph Desmond says he suffered a seizure and fell off his sofa on July 9. He went to the emergency room, where they ran an electroencephalogram (EEG) test, and then returned home. Within hours, he had a second seizure and went back to hospital.

His third seizure happened the next morning while walking to the nurse’s station.

In severe cases of listeriosis, bacteria can spread to the central nervous system and cause seizures, according to Health Canada.

“The last two months have really been a nightmare,” says Desmond, who has joined the proposed lawsuit.

When he returned home from the hospital, his daughter took a carton of Silk dark chocolate almond milk out of the fridge and asked if he had heard about the recall. By that point, Desmond says he was on his second two-litre carton after finishing the first in June.

“It was pretty scary. Terrifying. I honestly thought I was going to die.”

Cheryl McCombe, 63, Haliburton, Ont.

The morning after suffering a second episode of vomiting, feverish sweats and diarrhea in the middle of the night in early July, Cheryl McCombe scrolled through the news on her phone and came across the recall.

A few years earlier, McCombe says she started drinking plant-based milks because it seemed like a healthier choice to splash in her morning coffee. On June 30, she bought two cartons of Silk cashew almond milk.

“It was on the (recall) list. I thought, ‘Oh my God, I got listeria,’” McCombe says. She called her doctor’s office and visited an urgent care clinic hoping to get tested and confirm her suspicion, but she says, “I was basically shut down at the door.”

Public Health Ontario does not recommend listeria testing for infected individuals with mild symptoms unless they are at risk of developing severe illness, such as people who are immunocompromised, elderly, pregnant or newborn.

“No wonder they couldn’t connect the dots,” she adds, referencing that it took close to a year for public health officials to find the source of the outbreak.

“I am a woman in my 60s and sometimes these signs are of, you know, when you’re vomiting and things like that, it can be a sign in women of a bigger issue,” McCombe says. She was seeking confirmation that wasn’t the case.

Disappointed, with her stomach still feeling off, she says she decided to boost her gut health with probiotics. After a couple weeks she started to feel like herself.

But since then, McCombe says, “I’m back on Kawartha Dairy cream in my coffee.”

This report by The Canadian Press was first published Sept. 16, 2024.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

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B.C. mayors seek ‘immediate action’ from federal government on mental health crisis

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VANCOUVER – Mayors and other leaders from several British Columbia communities say the provincial and federal governments need to take “immediate action” to tackle mental health and public safety issues that have reached crisis levels.

Vancouver Mayor Ken Sim says it’s become “abundantly clear” that mental health and addiction issues and public safety have caused crises that are “gripping” Vancouver, and he and other politicians, First Nations leaders and law enforcement officials are pleading for federal and provincial help.

In a letter to Prime Minister Justin Trudeau and Premier David Eby, mayors say there are “three critical fronts” that require action including “mandatory care” for people with severe mental health and addiction issues.

The letter says senior governments also need to bring in “meaningful bail reform” for repeat offenders, and the federal government must improve policing at Metro Vancouver ports to stop illicit drugs from coming in and stolen vehicles from being exported.

Sim says the “current system” has failed British Columbians, and the number of people dealing with severe mental health and addiction issues due to lack of proper care has “reached a critical point.”

Vancouver Police Chief Adam Palmer says repeat violent offenders are too often released on bail due to a “revolving door of justice,” and a new approach is needed to deal with mentally ill people who “pose a serious and immediate danger to themselves and others.”

This report by The Canadian Press was first published Sept. 16, 2024

The Canadian Press. All rights reserved.

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