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Why Canada's decision to delay 2nd doses of COVID-19 vaccines may not work for everyone – CBC.ca

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New research from two small pre-print studies suggests delaying second doses of COVID-19 vaccines by up to four months may not be the best approach for some older Canadians.

The research comes as some experts are also questioning whether Canada’s vaccination advisers, who recommended the delay, can keep up with rapidly evolving science during the pandemic.

Prior to the pandemic, the National Advisory Committee on Immunization (NACI), which has provided guidance to the federal government on vaccinations since 1964, met just three times a year to discuss issues related to vaccines for influenza, mumps, measles and other viruses.

But a year after the pandemic was declared, with new data emerging daily, NACI has been thrust into the spotlight and forced to evaluate new vaccines for a novel virus faster than ever before.

“NACI’s committees are basically made up of volunteers, many with heavy daily responsibilities during the pandemic,” said Dr. David Naylor, co-chair of Canada’s COVID-19 Immunity Task Force.

“There’s no precedent for NACI to operate at this pace, and everyone is adapting on the fly.”

NACI has met nine times since Canada approved its first COVID-19 vaccine on Dec. 10, but it has plans to ramp up in the coming months with another 13 meetings scheduled between now and the end of June.

Guido Armellin, 86, receives the COVID-19 vaccine during a clinic at a church in Toronto on March 17. A team was on-site administering the Pfizer-BioNTech vaccine to parishioners as part of a community outreach program to get seniors vaccinated at their place of worship. (Evan Mitsui/CBC)

The committee has previously overturned its initial guidance against immunocompromised individuals and pregnant women receiving COVID-19 vaccinations, as well as a controversial decision against the AstraZeneca-Oxford vaccine for those over 65.

Delay could leave cancer patients less protected, U.K. study suggests

Perhaps one of NACI’s most impactful recommendations on Canada’s vaccine rollout was the decision to delay second doses beyond manufacturing guidelines by up to four months, but emerging research signals it may not be the best approach for vulnerable Canadians.

A new pre-print study, which has not yet been peer reviewed, analyzed 151 older cancer patients and compared their immune response with 54 healthy adults after receiving the first and second doses of the Pfizer-BioNTech COVID-19 vaccine in the U.K.

The researchers concluded that delaying second doses to between eight and 12 weeks for most cancer patients left them “wholly or partially unprotected” and had implications on their health and the potential emergence of coronavirus variants. 

WATCH | Delaying some 2nd COVID-19 vaccine doses challenged by new data:

New early data suggests that Canada’s recommendation of delaying the second dose of COVID-19 vaccines to up to four months may not be effective in some older, more vulnerable patients, causing the vaccine advisory committee to re-examine its guidance. 2:36

“Our data advocates that bringing forward the second dose of the vaccine for patients who have cancer may benefit them,” said Leticia Monin-Aldama, lead author of the study and a researcher at the Francis Crick Institute in London.

“And that perhaps a sort of one-size-fits-all approach may not be ideal when delivering these vaccines to the population.”

NACI advocated for that universal approach to delay second doses by up to four months for all Canadians — the longest interval recommended by a country so far — based on limited real-world evidence and the reality of Canada’s vaccine supply.

The decision was also informed by findings from Dr. Danuta Skowronski, epidemiology lead at the British Columbia Centre for Disease Control (BCCDC), who determined that one dose of the vaccine was actually more effective than clinical trials had initially shown.

NACI said if second doses were stretched to four months across the country, close to 80 per cent of Canadians over the age of 16 could get at least one shot by the end of June.

But Canada’s chief science adviser, Mona Nemer, has said the decision to delay second doses amounted to a “population level experiment” and advised against the delay in older Canadians on CTV’s Power Play this week, citing a lack of data to back up the decision.

Darryl Falzarano, a research scientist with the Vaccine and Infectious Disease Organization (VIDO) lab in Saskatoon, is also against the decision to increase the time between doses and said there is a growing body of research that suggests it’s not the safest approach for immunocompromised and older adults.

“The initial data look like delaying the dose of the mRNA vaccines would still provide reasonable protection to the population from severe or moderate disease, and so vaccinating more people was looked at as the greater good,” he said.

“Now, in certain populations — older people, people with comorbidities and cancers — likely delayed boosting for them is sub-optimal and possibly will lead to revised recommendations for those groups.”

Darryl Falzarano, a research scientist with the Vaccine and Infectious Disease Organization lab in Saskatoon, is opposed to increasing the time between doses and says there is a growing body of research that suggests it’s not the safest approach for immunocompromised and older adults. (Debra Marshall)

B.C. study analyzed long-term care residents

A second pre-print study released this week from researchers in British Columbia, which has also not been peer reviewed, cast further doubt on the dose delay for seniors and found that their immune response may not be as strong as in younger, healthier people.

The study analyzed antibody levels in a dozen long-term care residents in Vancouver a month after receiving their first dose of a COVID-19 vaccine, compared with 22 younger health-care workers — 18 of whom had not previously been infected by COVID-19 and four who had.

“The level of antibodies in older residents was fourfold lower, so significantly decreased,” said Dr. Marc Romney, a clinical associate professor at the University of British Columbia in Vancouver and one of the authors of the study. “The function of those antibodies in older people was also compromised.”

Romney said antibodies are just part of the picture, and he also plans to look at the immune system’s full response in future research. But he said the fact that antibodies in the elderly didn’t neutralize the virus as well as in the younger health-care workers suggests the dose delay may need to be revised for them.

“There is emerging evidence that demonstrates that there are some populations that will probably not fare as well and have the same degree of protection following single doses of a vaccine,” said Dr. Isaac Bogoch, an infectious diseases physician and member of Ontario’s COVID-19 Vaccine Distribution Task Force.

“These are groups you would want to shorten the time between dose one and two.”

WATCH | The science behind delaying the 2nd dose of COVID-19 vaccines:

Federal government scientists have put their support behind delayed second doses of COVID-19 vaccines — which several provinces were already doing — and ongoing research shows some of the benefits of the adapted strategy. 2:04

‘This isn’t a regular vaccine’

The speed with which NACI members are able to make these decisions has come under fire.

Falzarano said NACI is typically used to working under a “slow-moving” vaccine regulatory process where vaccines can take up to a decade to go from research to rollout.

“Their job is to review vaccines, but their experience is reviewing them under a much different scenario,” he said.

“They are normally looking at a full data set when they have to make decisions. They would normally make very conservative decisions, and now, they find themselves in a much different scenario than what they’re used to — and I think that’s highly challenging for them.”

Visitors to a mass vaccination clinic in Toronto on Tuesday fill in paperwork as they wait in line. The National Advisory Committee on Immunization initially recommended against giving the AstraZeneca-Oxford vaccine to seniors, but that guidance changed on March 16 after it reviewed data. (Frank Gunn/The Canadian Press)

NACI’s decision to recommend against the AstraZeneca-Oxford shot for seniors on March 1 came despite emerging evidence from around the world demonstrating its ability to prevent severe COVID-19 in older adults.

But that guidance changed on March 16 after more real-world data on the vaccine’s effectiveness was reviewed by NACI, and CBC News broke the story revealing documents on the federal government’s plans to allow those 65 and older to receive it.

Alyson Kelvin, an assistant professor at Dalhousie University and a virologist at the IWK Health Centre and the Canadian Centre for Vaccinology, all in Halifax, said NACI should include more experts in emerging viruses and vaccine development to help navigate the research in the pandemic.

“This isn’t a regular vaccine that’s gone through the typical workflow for vaccine approval and vaccine development because it’s an emerging virus,” said Kelvin, who is also evaluating Canadian vaccines at the VIDO lab in Saskatoon.

“You need somebody who understands that dynamic, instead of what we would normally depend on for our medicines or vaccines.”

Dr. Caroline Quach-Thanh, who chairs NACI, responded to criticism during a news conference on March 16, saying that as new evidence emerged on the efficacy of the AstraZeneca-Oxford vaccine in older adults, NACI was “busy with other files” that delayed its guidance.

“The committee is very busy, obviously, meeting weekly to discuss the emerging data on these important topics,” said Matthew Tunis, executive secretary to the committee.

“So there’s always inevitably going to be a bit of a lag between when a committee deliberates and when the advice is made public.”

Decisions take time, NACI chair says

Quach-Thanh responded to further questions about the delay in revising recommendations on CBC’s Power and Politics on Wednesday, noting that NACI isn’t equipped to review new evidence one day and make recommendations the next.

“It’s not possible, we can’t be that reactive,” she said. “I don’t think any advisory committee can be that reactive because it would mean that every time something changes, you move the needle one way or the next.

Dr. Caroline Quach-Thanh, who chairs the National Advisory Committee on Immunization, says NACI is currently re-examining its guidance based on new research, and new guidelines on the timing of second doses for seniors and the immunocompromised could come as early as next week. (Skype)

“Then it just means that you’re changing your recommendation every other day. So you need to gather that base of evidence before you change something.”

But even after NACI has finalized its recommendations, Quach-Thanh said, it takes an entire week to translate and upload them to the Public Health Agency of Canada’s website — precious time in a pandemic where new data emerges daily.

Quach-Thanh said the committee is currently re-examining its guidance based on new research, and new guidelines on the timing of second doses for seniors and the immunocompromised could come as early as next week. But Skowronski, with the BCCDC, said it’s too early to make that call definitively.

“This is a kind of a signal that we might want to follow, it’s of interest, but we cannot change or make policy on the basis of this sort of small study,” she said.

“It may come to pass that we will want to adjust depending upon how far we have come in achieving that goal of getting at least one dose into these individuals at highest risk.”

Skowronski defended the decision to delay second doses by up to four months in Canada and stressed that the benefits of vaccinating more vulnerable groups with an initial shot outweigh the risks of delaying a second.

“My preoccupation is in at least getting a first dose into those at high risk of severe complications, and we’ve not achieved that yet,” she said, adding that age was by far the biggest risk factor for severe outcomes from COVID-19.

“That’s job one. Let’s get that job one done, and then let’s debate the timing of the second dose.”

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Health Canada approves updated Novavax COVID-19 vaccine

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

The protein-based vaccine, called Nuvaxovid, has been reformulated to target the JN.1 subvariant of Omicron.

It will replace the previous version of the vaccine, 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.

Earlier this week, Health Canada approved Moderna’s updated mRNA COVID vaccine.

It is still reviewing Pfizer’s updated mRNA vaccine, with a decision expected soon.

This report by The Canadian Press was first published Sept. 19, 2024.

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

Note to readers: This is a corrected story. A previous version erroneously described the Novavax vaccine as an mRNA shot.

The Canadian Press. All rights reserved.

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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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