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Canadians may be eager to get a third dose of the COVID-19 vaccine to further protect themselves in the fourth wave, but the lack of evidence in favor of booster injections for the general public and the dire need for vaccines around the world should give us pause.
The World Health Organization recently called to stop the reinforcement Until the end of September at least, but rich nations are moving forward with plans for additional doses now regardless – Including parts of Canada.
Israel It has made the third doses of COVID-19 available to everyone age 30 or older, while we He plans to deliver reinforcements to anyone eight months after the second shot on September 20.
Other wealthy countries with adequate supplies of vaccines have taken a slightly more nuanced approach, with France, Germany and the United Kingdom Announcing third doses only to vulnerable populations at increased risk of decreased immunity to COVID-19.
But the health agency of the European Center for Disease Prevention and Control (ECDC) said Wednesday that there are No need to speed booster shots to the general public because all authorized vaccines provide high protection against hospitalization, severe illness, and death from COVID-19.
Now, with more than 67 percent of our total population After full vaccination, the question of whether Canada should give third doses to every eligible person to provide better protection against Deltas is on the table as other wealthy nations begin to roll out the boosters to the general public.
Do Canadians need boosters now?
The Canadian National Advisory Committee on Immunization (NACI) is currently balancing available data on the benefits of booster injections, and is expected to issue guidance soon. but Ontario And Alberta They’ve already started rolling it out for immunocompromised people.
“There are groups of people who don’t respond significantly to the vaccine,” said Dr. Zane Shagla, MD, an infectious disease physician at St. Joseph’s Healthcare in Hamilton and associate professor at McMaster University.
“Those who are at the most extreme of old age, those with significant immune disease, where a boost now probably makes sense.”
Canadian researchers at the University Health Network (UHN) in Toronto recently published a file Correspondence in the New England Journal of Medicine which showed evidence of ‘significantly higher immunity’ in transplant patients after a third dose.
A recent prepress study, which has not been peer-reviewed, of the Lunenfeld-Tanenbaum Research Institute at Sinai Health in Toronto, analyzed 119 long-term care residents of Ontario and 78 employees over a four-month period and found significantly lower levels of neutralizing antibodies in elderly patients — This indicates a possible need for a third dose in that group as well.
“But then it turns to – what do you do with the general population when studies suggest there is still significant protection?” Concerned said.
“There hasn’t been any data to suggest that getting a booster dose will really change their clinical picture.”
Delta booster ‘better’ for Canadians
While other countries are rushing to roll out third doses to the general public despite a lack of concrete long-term data – experts say it may be best to wait for a delta-specific booster to be developed to directly target the variant.
Moderna and Pfizer-BioNTech are currently working on updated mRNA vaccines designed specifically for emerging variants, but the third doses being rolled out in rich nations now are essentially additional snapshots of the original vaccine formulation.
But developing, testing and approving the new shot will take time—something not all of our experts agree.
Dr. Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases, said Friday Three doses of COVID-19 vaccines will likely be needed For complete protection, citing two Israeli pre-print studies that showed that a 10 times reduction in critical illness For those over 60 years old and Significant decrease in the odds of a positive test After three shots.
But the data limited range Experts point to a greater need for delta-specific booster shots for the general population, as opposed to third shots of the same formula, in order to target the devastating variant.
Dr. Allison McGuire, a medical microbiologist and infectious disease specialist at Mount Sinai Hospital in Toronto, says there are two primary reasons why developing a booster that specifically targets delta would be beneficial.
“One of them is that it gives you better levels of anti-Delta antibodies,” she said, which may provide better protection against primary infection and transmission than the variant.
The second involves something called a “fingerprint,” where your first experience with a virus or vaccine determines the nature of your immune system’s response.
“If we had delta as the new big thing, and your immune system was responding to it at first [the original strain]Then she said, “That wouldn’t be perfect.”
“It may be best – especially for children – to vaccinate them against Delta.”
It’s also best to wait until the antibodies start to fall off before giving an extra dose — so boosters may now speed up, says Alison Kelvin, assistant professor at Dalhousie University and a virologist at the Canadian Center for Vaccine Science and the Vaccines and Infectious Diseases Organization in Saskatoon. Does not make sense.
“I don’t think there is data to support, in healthy adults, that there will be a significant beneficial effect. You may see a rise in your antibodies, but also your antibodies may already be at their limit – so the boost may not be the timing,” she said.
Until we have more comprehensive real-world data, experts say if Canada is going to roll out boosters than we should start — and stop — with immunocompromised groups and older adults right now.
“If the question is asked today, do we all need a booster? The answer is no, no,” said Dr. Isaac Bogosh, an infectious disease physician at Toronto General Hospital and a member of the Ontario COVID-19 Vaccine Mission. duty.
Future variables pose an invisible threat
There is no doubt that the emergence of highly contagious variants of the coronavirus has been one of the biggest challenges to ending the epidemic in Canada and around the world.
New variants have appeared repeatedly throughout the epidemic in populations with low vaccine coverage that have been severely affected by uncontrolled transmission of COVID-19 – including India, South America and Africa.
The devastation caused by the original strain of the virus from Wuhan, China, has surpassed the emergence of the highly contagious virus. alpha And beta Variables in late 2020, which led to a brutal third wave in Canada and unleashed a mad rush to vaccinate people.
In the spring, Canada became one of the only countries in the world with a major outbreak Three different variables Speaking at the same time, we turned into a gigantic experience on the world stage.
But the Delta variant completely changed the battlefield, quickly usurping all the other variants into becoming the dominant strain in Canada by summer and exacerbating the fourth wave at a time when many believed the epidemic would be over.
Experts say the myopic approach of offering third doses to everyone, depends largely on raw data And unproven fears about Severity of penetration infections, fails to see the bigger picture of what is driving the emergence of variants in the first place: nearly half of the planet is without vaccines.
“Allow 3.5 billion people Staying vulnerable is a recipe for disaster that cannot be mitigated because worse and worse variables will emerge — not to mention millions of people who will die, said Dr. Madhukar Bay, professor of epidemiology and global health at McGill University in Montreal.
“It totally boggles my mind why world leaders, especially those who could and could have done something, chose to allow this injustice to continue.”
To put it in perspective, just 1.8 percent of people in low-income countries have received at least one dose of the COVID-19 vaccine, compared to more than 50 percent of those in rich countries.
Pai, who co-authored a Correspondence in the journal Nature As they quarrel this week about the need to vaccinate the developing world, he says stepping up efforts to vaccinate the world to prevent entirely new variants from emerging should be a global priority.
“We are now in a fourth wave because of the delta. There is no way to prevent the worst variants from not only emerging, but also from coming to our countries,” he said. He wants to see rich nations immediately come together, donate vaccines and fund global industrialization.
“Because if we don’t, we’re in this forever.”