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Canada just approved Latest COVID-19 vaccine It targets the first highly contagious Omicron variant and is expected to start rolling out within days. But what exactly can we expect when these new shots land in the real world?
The updated Moderna vaccine, also known as a “bivalent” vaccine, is a combination of two strains that kills both the original virus and the Omicron variant BA.1 that emerged late last year and caused an outbreak. targeted. Largest wave of infections and hospitalizations in a pandemic.
The new shot does not directly target the dominant Omicron variants BA.4 and BA.5, but US approved updated shots Pfizer this week submitted The BA.4-5 vaccine was submitted for Health Canada approval on Friday, and Moderna is expected to be submitted soon.
“The evidence we have obtained so far indicates that bivalent vaccines containing BA.1 offer excellent protection against BA.4 and BA.5,” said Deputy Chief Public at Thursday’s technical briefing. Health Director Dr Howard Njou said.
“Certainly, as the situation evolves, the evidence will need to be examined to see what happens with real-world validity.”
But what the latest booster can do depends on how fragile your immune system is, whether you’re one of the millions of Canadians who recently contracted COVID, or when you were last vaccinated. .
Will the latest vaccine stop the spread of COVID?
Infectious disease experts, virologists, epidemiologists and immunologists hope that the updated vaccine will be more effective in preventing transmission than the original vaccination, but at least initially, Canadians warns against expecting them to be silver bullets.
Data on the impact of these vaccines are limited, so all eyes will be on their effectiveness in reducing infection and transmission rates and whether they will better protect vulnerable groups of the population heading into the autumn and winter months. will be directed.
Chief Public Health Officer Teresa Tam said at a news conference on Thursday when asked how effective the latest vaccine would be in stopping the spread of the virus, she said: “Because it’s not available, we don’t know what its impact will be. I don’t know if it is,” he said.
Tam said he hopes Moderna’s new bivalent BA.1-targeted vaccine will provide increased protection against infection and transmission through at least the fall.
Clinical Trial Data on BA.1 Targeted Vaccines from Moderna When Pfizer – BioNTech They suggest providing slightly stronger immune protection against Omicron than the original vaccine, but we still don’t know what exactly that means in the real world.
Dr. David Naylor, co-chair of the federal government’s COVID-19 Immunity Task Force, said:
“However, even if their marginal benefits are small, rekindling public interest in their novelty boost can have a meaningful positive impact.”
new Preprint modeling studiesNot peer reviewed.
But it could lead to significant protection at the population level, with preprints resulting in an average of 8 fewer hospitalizations for every 1,000 people vaccinated with the latest booster compared to the original vaccine. also suggests.
“We don’t yet know the scale of this improvement, but it will be fairly limited,” said Dr. Gaston de Ceres, an epidemiologist at the National Institute of Public Health of Quebec (INSPQ).
“Historically, the original [vaccines] Quite successful. “
What does the latest COVID vaccine bring you?
With more than half of Canadians infected with COVID since the emergence of Omicron and its highly contagious variants, added protection from previous infections in vaccinated populations provides an advantage It seems that
New research letter published in New England Journal of Medicine A study of the risk of BA.5 infection in Portuguese populations previously infected with past variants such as BA.1 and BA.2 showed strong protection against new variants. understood.
This is partly because Portugal has a very high vaccination coverage, with over 98% of the population surveyed receiving at least two doses. This means that, as in Canada, her high level of two-dose vaccination and infection provides strong immune protection.
Two Canadian preprint studies from May When JuneIn a non-peer-reviewed study, we also found that previous Omicron infection, especially when combined with vaccination, provides strong immunity against future reinfection and hospitalization.
“In general, we hybrid immunity Dr. Danuta Skowronski, vaccine efficacy expert, chief of epidemiology at the BC Centers for Disease Control and co-author of the preprint, said:
“It’s also true that vaccine strains that better match prevalent variants are likely to offer better protection.”
Waiting longer after the last infection or vaccination is also important to consider, and emerging evidence suggests that having boosters too close after an infection or vaccination can affect the effectiveness of shots. is appearing in
new small preprint researchNot peer reviewed.
Recommended by NACI wait 3 months after infection Before I get another shot The dosing interval is 3–6 months, But the latest guidance also says fall boosters should be offered to those at high risk of severe COVID in Canada.
“Timing is everything, and the general recommendation is to wait a few months after infection before getting a booster shot,” Skowronski said.
She added that one should not rush to get a booster immediately after infection as it can actually interfere with the immune response.
Updated vaccine ‘helps’ but not a ‘miracle’
In Canada, there are still “anxious gaps” in the coverage of the third dose, Naylor said. less than half of Canadians I received a booster even though it was offered significant additional protection Against severe COVID-19.only about 12% I received my 4th dose.
Deepta Bhattacharya, professor of immunobiology at the University of Arizona, said: .
“Given that the BA.5 is still in circulation, I don’t think there’s any downside to picking up these boosters. They’ll probably work better than another shot of the original.”
Bill Hanage, an epidemiologist at the TH Chan School of Public Health at Harvard University in Boston, said even if the original vaccine wasn’t an exact match for Omicron, it provided strong protection against serious illness. said it is important to consider
“But a closer match should do more,” he said in an email.
Bhattacharya said the “big question” now on the mind is how effective the updated vaccine will be in stopping transmission in the real world, and how long it will last.
“Will these boosters start to restore some of the protection against infections and symptomatic infections? I think they will,” he said. I think it should.”
Dr. Allison McGeer, a medical microbiologist and infectious disease expert at Toronto’s Mount Sinai Hospital, said the latest shots may slightly increase neutralizing antibodies that prevent transmission, adding that the additional protection is “what There is no such thing.
“The booster dose of the original vaccine provides a significant boost in protection against BA.4 and BA.5. It’s not perfect, but I think you know that nothing is perfect,” she said. “The bivalent vaccine may be a little better, but it won’t be a miracle.”
Bhattacharya said clinical trials have shown only about a 2-fold increase in protective antibodies against the BA.1, BA.4 and BA.5 variants targeted by Moderna and Pfizer in their bivalent vaccines, but still said to have a significant protective effect.
“If you look at the data, there are a lot of antibodies being made,” he said. “So I have good reason to expect them to help — and probably help a lot.”