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New data suggests Canada's 'gamble' on delaying, mixing and matching COVID-19 vaccines paid off – CBC.ca

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This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven’t subscribed yet, you can do that by clicking here.


New Canadian data suggests the bold strategy to delay and mix second doses of COVID-19 vaccines led to strong protection from infection, hospitalization and death — even against the highly contagious delta variant — that could provide lessons for the world.

Preliminary data from researchers at the British Columbia Centre for Disease Control (BCCDC) and the Quebec National Institute of Public Health (INSPQ) shows the decision to vaccinate more Canadians sooner by delaying second shots by up to four months saved lives.

The researchers excluded long-term care residents from the data, who are generally at increased risk of hospitalization and death from COVID-19, in order to get a better sense of vaccine effectiveness in the general population — and the results were exceptional. 

The analysis of close to 250,000 people in B.C. from May 30 to Sept. 11 found two doses of any of the three available COVID-19 vaccines in Canada were close to 95 per cent effective against hospitalization — regardless of the approved vaccination combination

That means for every 100 unvaccinated people severely ill in Canadian hospitals, 95 of them could have been prevented by receiving two doses of either the AstraZeneca-Oxford, Pfizer-BioNTech and Moderna vaccines, or some combination of the three.

Dr. Danuta Skowronski with the B.C. Centre for Disease Control laid the groundwork for the decision to hold back second doses and says the early vaccine effectiveness data is extremely encouraging. (Harman/CBC)

Dr. Danuta Skowronski, a vaccine effectiveness expert and epidemiology lead at the BCCDC whose research laid the groundwork for the decision to hold back second doses based on the “fundamental principles of vaccinology,” says the early data is extremely encouraging. 

“We were very pleased to see during the period when the delta variant was not just circulating, but predominating, that we had such high protection nonetheless against both infection and hospitalization,” the lead researcher on the analysis told CBC News. 

“Protection was even stronger when the interval between the first and the second doses was more than six weeks apart.”

In fact, the research showed that protection against COVID-19 infection from two doses of the Pfizer vaccine rose dramatically when the first and second shots were spread out — from 82 per cent after three or four weeks, to 93 per cent after four months. 

“For those who received the AstraZeneca vaccine as their first dose, their protection against any infection was lower than for mRNA vaccine recipients, but they had comparable protection against hospitalization and that’s the main goal,” she said.

“But for those who received a first dose of AstraZeneca and a second dose as an mRNA vaccine, their protection was as good as those who had received two mRNA vaccines. So that’s also a really important finding from this analysis.”

While the work is still being finalized and has not yet been submitted as a pre-print or undergone peer review, the researchers felt it’s important to get their early data out now to inform the public and policymakers here and abroad about the positive results. 

“The mix-and-match schedules are protecting well, and my preference would be that those countries who don’t recognize that get to see our data as soon as possible,” she said, adding that the findings were sent to U.S. officials for review of international travel policies

“My hope is that when they see the evidence that they will change those policies, which are frankly inconsistent with the science.” 

Quebec data backs up findings from B.C.

In Quebec, thousands of kilometres away and with a different population, demographic makeup and early vaccine rollout approach — the results of a twin study that will be published alongside the B.C. data were astonishingly similar. 

Of the 181 people who died from COVID-19 from May 30 to Sept. 11 in Quebec, just three were fully vaccinated. Researchers say that corresponds to a vaccine effectiveness against death upwards of 97 per cent based on a population analysis of nearly 1.3 million people. 

Similar to the B.C. data, the Quebec research also showed more than 92 per cent protection from hospitalizations — with Pfizer, Moderna or AstraZeneca vaccines — against all circulating coronavirus variants of concern in Canada at that time, including delta.

“The takeaway is whatever vaccine people had, if they got two doses they should consider that they are very well protected against severe COVID-19,” said Dr. Gaston De Serres, an epidemiologist at the INSPQ. “That’s the main message.”

The analysis found Pfizer and Moderna vaccines were 90 per cent effective at preventing COVID-19 infections — either asymptomatic, symptomatic, or those needing hospital care — a protection rate equal to those with an AstraZeneca and mRNA vaccine combination.

For people who received two doses of AstraZeneca, the research suggests a slightly lower level of protection from infection — but one that is still remarkably high at 82 per cent. 

The research showed that protection against COVID-19 infection from two doses of the Pfizer vaccine rose dramatically when the first and second shots were spread out. (Darryl Dyck/The Canadian Press)

De Serres says the National Advisory Committee on Immunization (NACI) and the Quebec Immunization Committee (CIQ) are looking at whether additional doses may be needed for that group, but says it’s “not as pressing” given the strong protection from hospitalization. 

“For the time being, just stay put. If there is a recommendation for you to get an additional RNA dose you’ll know in time,” De Serres said. “But feel that what you’ve got is still a very good regimen to protect you against what we fear most — which is severe COVID-19.”

The NACI recommendation in March to delay second doses of all three COVID-19 vaccines by up to four months was not without controversy at the time, and no doubt led to confusion among many Canadians about whether they were adequately protected. 

Canada’s Chief Science Adviser Mona Nemer said in early March that the strategy amounted to a “population level experiment,” while at the same time health officials tried to reassure the public that the approach was safe and effective. 

Deepta Bhattacharya, an immunologist at the University of Arizona who was not involved in the study, says the results are “very encouraging” and provide evidence of “improved real world protection” from delaying second doses.

But he admits even he was initially skeptical. 

“I was uneasy about it in large part because I just wasn’t sure how well the protection would hold up in the interim,” he said. “Obviously it turned out well … but it was risky, and that gamble paid off.”

Bhattacharya says the Canadian data now provides real world evidence that vaccinated people produce more antibodies if their second shot is delayed, and the quality of those antibodies may actually improve — which could explain the better protection against delta. 

“What I’m really wondering now going forward is whether the recommendations are going to fundamentally change as to when we should get that second shot,” he said, referring to other countries around the world. “I wish I’d gotten mine later now in retrospect.” 

Keeping ‘eye on the prize’ means avoiding hospitalization

The data also has implications on whether average Canadians need booster shots, particularly given that emerging real world data in other countries like the U.S., Israel and Qatar show evidence of waning immunity that has prompted the rollout of third doses.

But experts caution that while countries reporting diminished vaccine effectiveness against COVID-19 infection may be making headlines, the more important factor is that the studies largely show the vaccines have prolonged protection against severe COVID-19 — meaning hospitalization and death.

“We really should keep our eyes on the prize, which is preserving healthcare system capacity and preventing unnecessary suffering,” said Skowronski. “We’re not going to prevent every case of COVID-19. Our goal was never to prevent the sniffles. Our goal was to prevent serious outcomes.” 

Still, the B.C. and Quebec data showed “no signs” of waning immunity in the general population four months after the second mRNA dose and strong protection against infection of more than 80 to 90 per cent maintained. The analysis doesn’t go beyond five months, but the researchers will continue monitoring vaccine effectiveness.

“We should be reassured that our vaccine effectiveness from this calculation, from what I’ve seen, will be robust with its protection,” said Alyson Kelvin, an assistant professor at Dalhousie University and virologist at the Canadian Center for Vaccinology and the Vaccine and Infectious Disease Organization in Saskatoon who was not involved in the research.

“We must continue to have public health measures in place as well as expect at some point we might need a booster, but data like this will inform when we do and right now it’s suggesting that we don’t need it yet — but we have to keep vigilant.” 

WATCH | Canada recommends COVID-19 booster shots for long-term care residents:

NACI recommends COVID-19 booster shots for seniors in long-term care

10 days ago

Amid a global debate over COVID-19 vaccine boosters, the National Advisory Committee on Immunization is recommending third doses for Canada’s most vulnerable, especially seniors in long-term care homes. 1:58

Skowronski says that while she supports giving long-term care residents and immunocompromised people third doses of COVID-19 vaccines to increase their protection based on emerging data, including from Canada, there isn’t enough evidence yet for average Canadians. 

Until then, she says Canadians should feel well protected against severe outcomes from COVID-19 in the delta-driven fourth wave if they’re fully vaccinated with any of the approved vaccine combinations in Canada. 

“We’re going to have to learn to live with SARS-CoV-2, including in it’s very many future iterations,” she said. 

“But so long as we can prevent severe outcomes and maintain healthcare system capacity, we can come to a kind of a mutual understanding with this virus.” 

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Parents more hesitant to vaccinate kids than themselves, researcher says – Clearwater Times

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Jennifer Hubert jumped at the opportunity to get her COVID-19 vaccine, but she’s not looking forward to having to make the decision about whether to vaccinate her three-year-old son Jackson.

She recognizes the safety and effectiveness of vaccines, but said she also understands her son is at a much lower risk for serious illness than older adults.

“To me it’s not a clear benefit,” she said.

While many parents were overjoyed at the news that Health Canada is considering approval of the first COVID-19 vaccine for kids age five to 11 in Canada, parents like Hubert are feeling more trepidatious, and public health officials said they are going to have a much more nuanced conversation with parents about vaccination than they did with adults.

While 82 per cent of eligible Canadians aged 12 and up are already fully vaccinated, a recent survey by Angus Reid shows only 51 per cent of parents plan to immediately vaccinate their kids when a pediatric dose becomes available.

Of parents with children in the five to 11 year age range, 23 per cent said they would never give their kids a COVID-19 vaccine, 18 per cent said they would wait, and nine per cent said they weren’t sure, according to the survey of 5,011 Canadians between Sept. 29 and Oct. 3, which cannot be assigned a margin of error because online surveys are not considered random samples.

“Most of the research that I’ve seen sort of indicates that parents are more hesitant to vaccinate their kids against COVID than themselves,” said Kate Allan, a post-doctoral fellow at the Centre for Vaccine-Preventable Diseases at the University of Toronto.

There are several reasons parents might pause, she said.

It’s true that children are at a much lower risk of serious outcomes associated with COVID-19, and there have been very rare incidents of mRNA vaccines like Pfizer or Moderna linked to cases of myocarditis, a swelling of the heart muscle.

As of Oct. 1, Health Canada has documented 859 cases associated with the vaccines, which mainly seem to affect people under 40 years old, and people who’ve developed the complication have typically been fine.

READ MORE: 51% of parents ready for COVID jab, as Pfizer asks for Health Canada OK to vaccinate kids

“I know it’s rare, I know it’s not deadly, but I also see the risk of severe symptoms from COVID as being rare and not deadly for Jackson,” Hubert said when asked about weighing up the risks and benefits of the vaccine.

But public health experts stress that some children do suffer from rare but serious impacts from COVID-19, which can also cause myocarditis as well as the little-understood impacts of the condition known as long COVID.

They say parents should consider the less tangible benefits of vaccination as well.

“It’s less of a conversation about a direct benefit to them, and more of a community benefit,” Allan said.

The pandemic has taken a heavy toll on children, depriving them of school, time with their peers, extracurriculars — and their mental health has suffered as a result, said Dr. Vinita Dubey, associate medical officer of health with Toronto Public Health.

“Not one child has been spared from this pandemic. I mean every single child has had to bear a sacrifice because of the pandemic in one way or the other,” Dubey said.

So far Pfizer-BioNtech is the only manufacturer to request approval for its pediatric COVID-19 vaccine and Health Canada is still reviewing the data.

The regulator has promised the review will be thorough, and the vaccine will only be approved for children if the benefits outweigh the potential risks.

Policy-makers know they’re going to have to take parents’ concerns seriously as well.

On a recent tour of the Children’s Hospital of Eastern Ontario in Ottawa, Prime Minister Justin Trudeau spoke with Dr. Anne Pham-Huy, a pediatric infectious diseases physician.

“Vaccine confidence is going to be the most important part of it this time around,” Pham-Huy said, to which Trudeau agreed.

Dubey has published research on improving parents’ vaccine confidence when it comes to long-established inoculations like mumps and rubella.

While she offered several tips, they mainly come down to building trust. Her research focused on the role of family doctors, but she said during the pandemic anyone can be that trusted sounding board.

“It could be a faith leader, it could be an important family member or friend, someone who you trust, to help guide you to the right sources to make that decision,” she said.

With that in mind, several students from across North America launched a peer-to-peer education program called Students for Herd Immunity to allow kids to have those conversations among themselves.

The public health experts agree, the debate around vaccines has become polarized and open conversations will be the key to addressing parents’ concerns.

“I think one thing to say to parents is you don’t have to make your decision right away,” Dubey said. “I mean for those who are ready to make their decision, but it’s fine but if you have questions, seek the answers.”

Her only advice is to get those answers from a trusted source, and not social media.

READ MORE: Pfizer will ship millions of vaccine doses for kids as soon as it’s approved, Trudeau says

Laura Osman, The Canadian Press


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Sask. to offer monoclonal antibodies to some COVID-19 patients – Flipboard

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Saskatchewan won’t impose more COVID-19 measures: Premier Scott Moe

The Toronto Star – The Canadian Press • 16h

REGINA – Saskatchewan Premier Scott Moe says he will not bring in additional COVID-19 measures because it ultimately takes away people’s personal …

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EOHU recommending flu shots for area residents, as winter approaches – The Review Newspaper

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As the fall and cooler weather arrive, they bring with them the start of flu season. According to the Eastern Ontario Health Unit, the flu shot is the best protection against the flu, and with the presence of COVID-19 in the community, getting your flu shot is more important now than ever. The flu shot has been approved for use alongside COVID-19 vaccines and is a key step in keeping healthy this season.

“It’s especially important that people get their flu shot this year,” says Dr. Paul Roumeliotis, Medical Officer of Health at the Eastern Ontario Health Unit (EOHU). “Both COVID and the flu share symptoms and, despite their similarities, being fully vaccinated for COVID won’t protect you from the flu.”

“Getting the flu shot can help you stay healthy and reduce the pressure on health care centres.”

Getting the flu shot could also help reduce the demand on COVID-19 assessment centres. The fewer number of people who develop flu symptoms, the fewer who will need to get tested for COVID-19.

The flu shot is available at various locations throughout the five Eastern Counties and Cornwall, including through some healthcare providers, community health centres, participating pharmacies and by appointment at the EOHU for children ages 6 months to under 5 years, and their immediate family.

Appointments for children at the EOHU will be available as of November 1. Call to book your child’s appointment starting on October 25. Residents must bring a piece of identification to their appointment. To find out more about where you can get the flu shot, visit EOHU.ca.

Certain groups of people are at higher risk of complications from the flu and are strongly encouraged to get immunized. These include:

  • children 6 months to less than 5 years of age
  • people aged 65 and older
  • people with chronic medical conditions

If you live with or provide care to someone who falls under one of the groups listed above, or care for newborn infants and children under 6 months of age, it is also highly recommended that you get immunized. This simple step will help protect you and those around you.

For more information about the flu shot, visit EOHU.ca or call  613-933-1375 or 800-267-7120.

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