Are 4th doses of COVID-19 needed amid the spread of Omicron? Experts are weighing

It’s been six months since Canada opened the COVID-19 booster shot for all adults in the country, and now many are wondering if it’s time for them to get another one.

Nearly 50 percent Canadians have received their third dose of the COVID-19 vaccine, but fourth doses are currently only recommended for certain high-risk groups.

National Advisory Committee on Immunization (NACI), which advises the federal, provincial, and territorial governments on vaccine use, strongly recommended a second booster vaccine in April 2022 for adults aged 80 and over, and residents of long-term care facilities or other congregate settings.

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As new options become available, experts say a fourth COVID-19 shot should become more widely available.

The NACI previously recommended that people with “moderate or severe immunodeficiency” receive a fourth dose of the COVID-19 vaccine six months after their third shot.

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The healthy population in general should not be rushed to get a fourth dose, experts say, given single-dose protection, low transmission rates of the virus, and outdoor social interactions during the summer months.

“I don’t think there is an absolute requirement for a fourth [shot] at this point in time,” said Ciriaco Piccirillo, an immunologist and senior researcher at the McGill University Health Center (MUHC) Research Institute.






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COVID-19: Canada should prioritize 4th dose for adults over 80 living in long-term care facilities, NACI reports – April 5, 2022

According to the NACI, the booster dose is intended to restore protection that may have declined over time or is no longer sufficient in individuals who initially responded adequately to a full course of primary vaccination.

Antibody levels tend to naturally decline about four to six months after vaccination, Piccirillo said.

“If we get promoted again, those levels will go up again,” he told Olx Praca.

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While getting a fourth dose is not a disadvantage now, people should consider their individual risks and consult with their doctor before deciding on another shot, said Omar Khan, a professor of biomedical engineering and immunology at the University of Olx Praca.

“Indeed, the question to ask yourself is: ‘What is the likelihood that I will be exposed, and what is my level of risk?'” he said.






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Meanwhile, prior infection with COVID-19 should also be considered when determining your vaccination status, said Michael Grant, a professor of immunology at Memorial University of Newfoundland.

“In every study so far, infection has been equivalent to at least one dose of vaccine,” he said during a Zoom webinar on Thursday hosted by the COVID-19 Immunity Task Force.

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“And in some conditions, especially when it’s a severe infection, it induces better immunity.”

Waiting for updated vaccines

Data on the effectiveness of the fourth dose of COVID-19 is limited.

According to a study published in the journal New England Journal of Medicine In May, a fourth dose of the COVID-19 vaccine given to people over 60 in Israel made them twice as resistant to Omicron infection as triple-vaccinated people in the same age group.

Meanwhile, another study from Israel in January indicates that the fourth dose of the coronavirus vaccine provides only limited protection against the highly transmissible Omicron variant.

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The current booster shots are exactly the same formula as the first two doses, based on the original COVID-19 strain from Wuhan.

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Grant says questions are being raised about the value for healthy young adults of getting an extra boost with an inherited spike protein that may no longer exist.

“It will raise your antibodies somewhat, but definitely not selectively raise them for Omicron and the newer variants,” he said.






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Fact or Fiction: Experts Say Omicron Infection Causes Shorter Immunity – April 8, 2022

As the virus mutates, Pfizer and Moderna are currently testing an updated version of their COVID-19 vaccines in late-stage clinical trials to better target the Omicron variant and its subtypes.

Both companies hope their modified vaccine will be ready for approval in the fall.

This is another option to consider in the coming months.

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4th dose of COVID-19 vaccine: what is the scientific background of the next booster dose?

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So, should Canadians wait for an updated vaccine or get immunized now?

It’s not an either-or decision, and whatever you decide will depend on your individual risks, U of T’s Khan said.

“Both options are great,” he said.

“Having one-fourth dose of the current vaccine instead of a booster with the new version… you can do both. It’s not a problem.”

Piccirillo agreed, adding that a generally healthy population could “probably wait” until the fall for any booster available.

“It would probably be more strategic to introduce a fourth booster vaccine, preferably with a variant-tailored vaccine, perhaps late summer, early next fall,” he said during a CITF webinar on Thursday.

– with files from The Canadian Press and Reuters

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