COVID-19 vaccine: second dose delay is “riskier” for the elderly, warn experts

COVID-19 vaccine: second dose delay is

Alberta seniors Paddie Walmsley and her husband received their first injection of the AstraZeneca COVID-19 vaccine earlier this month, shortly after the province began offering limited doses to Albertans aged 60 to 64 years.
While the couple feel relieved and lucky, they are also worried about the long wait until July before they can receive their second dose.

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“It’s worrying. We would feel better protected and more confident if we could get the second dose sooner than four months, ”said Walmsley, 60, from Coaldale, a town about 230 km south of Calgary.

On March 3, Canada’s National Advisory Committee on Immunization (NACI) updated its guidelines, recommending that provinces and territories extend the time between the first and second dose of the COVID-19 vaccine to four months , from the initially prescribed period of three to four weeks, with vaccine shortages.

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NACI said extending the dosing interval will contribute to “opportunities for the protection of the entire adult population in a short period of time.”

The governments of Ontario, Alberta, British Columbia and Manitoba have opted for their plans for deployment outside of long-term care facilities.

But many experts say the elderly, as well as the vulnerable population, who have a weaker immune response, should be exempt from this rule.

Paddie Walmsley says she feels lucky to have at least the first dose of COVID-19 vaccine.

Photo provided by Paddie Walmsley

“The elderly… have the weakest immune system among us and COVID-19 is plagued by it,” said Samir Sinha, director of geriatrics at Sinai Health Hospitals and University Health Network in Toronto.

“This ‘one-size-fits-all’ approach to delaying the second dose of the vaccine for up to 16 weeks may not be suitable for everyone.”

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The concerns stem from growing data from the UK – where Pfizer and AstraZeneca vaccines are given 12 weeks apart – which suggests that the second dose is crucial to get the full benefit from the vaccine for the elderly population.

Looking at the scientific evidence, the first dose drops much faster than the two doses, said Jorgan Fritz, an immunologist at McGill University.

The decline is “clearly high” in the elderly and immunocompromised, he told Global News.

“The concern of the scientific community is that we are vaccinating without creating an effective immune response by making this increased spacing of the two doses,” said Fritz.

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Vaccine makers Pfizer and Moderna offer 21 and 28 day intervals, respectively. The protocol for administering the booster kit and used in clinical trials with AstraZeneca was one month after the first dose.

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In a statement to Global News, Health Canada said, “NACI is aware of the first emerging evidence of variable immune responses in immunocompromised people.

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In the coming weeks, the committee will review the extended interval strategy, he added.

Derek Phillips, 82, from Toronto, Ont., Received his first dose of Moderna vaccine at Seneca College last Saturday.

He said he was surprised when told his appointment for the second dose would be after 14 weeks and not four weeks as stated on the brochure from the provincial health department.

When questioning the change in schedule, a woman at the vaccination site said, “We could call you sooner,” Phillips said. Its main concern is to obtain the “optimal medical benefit”.

« I don’t think there should be any uncertainty, ”added the dual Canadian-British citizen.

“That does not make sense.”

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Reservation for COVID-19 vaccinations now available for Ontarians 75 and over

Reservation for COVID-19 vaccinations now available for Ontarians 75 and over

Tania Watts, immunologist and professor at the University of Toronto, said delay in people aged 80 and over was “riskier” than delay in younger ones.

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“So while everyone benefits from boosting the immune system with a second dose, the delay is more severe in people at greater risk, such as cancer patients, the elderly, the immunocompromised,” she said. told Global News.

Meanwhile, re-infection of COVID-19, while rare, is a concern for older people.

A large-scale peer-reviewed study published in the medical journal Lancet on March 17 found that most people who have had COVID-19 are protected from catching it again for at least six months, but elderly patients over 65 are more prone to reinfection than younger people.

Earlier in March, an outbreak at a long-term care home in Gatineau, Que., Where 96% of residents and 41% of staff had been vaccinated with a first dose, killed five residents.

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In Canada, the population aged 60 and over is responsible for more than 95% of deaths from COVID-19.

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“If the goal is to save as many lives as possible, then we would consider shortening this second interval,” Sinha said.

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The spread of more transmissible variants has also raised questions about the effectiveness of vaccines, with some studies showing reduced antibody protection.

In addition to strict adherence to the recommended dosage regimen used in clinical trials by vaccine manufacturers, Fritz said the elderly and vulnerable should also be boosted starting in November to provide the “best immune protection” for. Winter.

“There are concerns that a suboptimal immune response may lead to an increase in the appearance of viral variants,” he said.

– With files from Linda Boyle and Su-Ling Goh of Global News

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© 2021 Global News, a division of Corus Entertainment Inc.


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