As more evidence emerges about the effectiveness of the third dose of the COVID-19 vaccine, experts say it’s time for public health authorities to review the definition of “fully vaccinated” to include a booster dose.
While most SARS-CoV-2 vaccines available in Canada were initially developed and tested to include two doses, with the exception of the Johnson & Johnson vaccine, a primary course should consist of three doses, he said. Colin Furness, an expert in infectious diseases. epidemiology of the University of Toronto.
“Someone who has only been vaccinated twice will say, ‘I’m totally vaccinated,'” and that’s what the authorities say. [but] authorities have been wrong, “Furness told CTVNews.ca in a telephone interview on June 1.” When we look at the decline in immunity after the second dose, this is really a three-dose vaccine. “
A recently published meta-analysis conducted by the Chinese University of Hong Kong earlier this year evaluates the effectiveness of different combinations of vaccines to protect against COVID-19. With 53 studies involving more than 100 million people, the meta-analysis showed that three doses of an mRNA vaccine were very effective in protecting against COVID-19 infection, either symptomatic or asymptomatic, by 96%.
Three doses of an mRNA vaccine also had a 95 percent efficacy rate to reduce COVID-19-related hospitalization. The study concludes that three doses of a COVID-19 vaccine are needed to protect against infection with the Omicron variant of the virus.
Despite this, the Public Health Agency of Canada’s (PHAC) definition of “fully vaccinated” for COVID-19 vaccines continues to refer to those who have received a primary vaccine series. The primary series includes two doses of most vaccines approved for use in Canada (such as mRNA vaccines, as well as AstraZeneca, Novavax, and Medicago vaccines) or one dose of Johnson & Johnson vaccine.
“As the epidemiological context of COVID-19 continues to evolve, the Government of Canada will continue to monitor the efficacy and effectiveness of vaccines used in Canada and may offer further recommendations on the definition of a fully vaccinated person.” said PHAC spokeswoman Anna Maddison. wrote in an email to CTVNews.ca on June 1.
It is important to note that as the COVID-19 pandemic has progressed, the SARS-CoV-2 virus has evolved away from the vaccines that were initially developed to be targeted, Furness said. This viral evolution has led to a reduction in the effectiveness of current vaccines, especially with regard to protection against Omicron infection, the new variant of concern. Despite this, three doses of the vaccine continue to offer strong protection, especially against serious COVID-19 outcomes, such as hospitalization and death, Furness said. As a result, he said he expects to see a change in the definition of “fully vaccinated.”
“Hypothetically, if we had a vaccine that prevented COVID, hospitalization, and long death, but it didn’t stop anyone from getting infected, I’d say it’s a big hit; we’d all catch a cold … but no one would get very sick.” said Furness. “There is no doubt that we do not have it, but three doses of a vaccine against COVID-19 bring us closer to that.
“When we talk about ‘totally vaccinated’, we should talk about three [doses]. ”
In Canada, just over 20 million third and fourth doses of the COVID-19 vaccine have been administered to date, according to data compiled by CTVNews.ca. According to PHAC, about 55.5 per cent of Canadians aged 12 and over are vaccinated with three doses of the COVID-19 vaccine, which translates to approximately 18.5 million people.
‘COMPLETELY VACCINATED’ IS NO LONGER ENOUGH
University of Saskatchewan epidemiologist Dr. Nazeem Muhajarine also advises those who are eligible for their third dose of COVID-19 vaccine to receive it. However, instead of linking the definition of “fully vaccinated” to a specific dose number, he said public health authorities should focus on advising Canadians to keep their vaccination status “up to date” according to the latest recommendations of the National Advisory. Immunization Committee (NACI).
“‘All vaccinated’ no longer works, in my opinion, as a definition of being up to date on the doses of vaccine to be received … I think it’s time to [change] “This is about keeping up with all the vaccines you are recommended to get at this stage of the pandemic,” he told CTVNews.ca on June 1.
The current definition of the World Health Organization’s primary vaccination series refers to one or two doses of COVID-19 vaccines approved for emergency use, depending on the product. In the context of international travel, the Government of Canada considers that people with at least one dose of the Johnson & Johnson vaccine, or two doses of any of the remaining vaccines approved for use in Canada, are fully vaccinated. Provincial governments, such as Ontario, have updated their latest guide to suggest that people be vaccinated with “all recommended doses of COVID-19 vaccine, including booster doses when eligible.” “.
In addition, provinces across Canada have made the third dose available to people 12 years of age and older, and the NACI strongly recommends the third dose for all adults in Canada.
Although Furness said she admits that vaccine protection against COVID-19 may also decrease after a third dose, she still recommends that those who are eligible to receive their booster vaccine do so, given the additional protection. which offers compared to only two doses.
“It may slow down, but it would still interrupt the transmission and stop the outbreaks, if we could get enough people. [vaccinated] with a third dose, “he said.
A third dose of the COVID-19 vaccine will also help further protect populations from new variants or subvariants that may arise in the future, Muhajarine said.
“As long as we have multiple variants that extend, that opens up the possibility of new variants emerging; that’s how these variants evolve,” he said. “I really don’t see any evidence-based reason to keep ‘completely vaccinated’ with just two primary doses.”
Absorption of the third dose of COVID-19 vaccine has been slow compared to the first and second doses, both Furness and Muhajarine said. Part of the reason for this is that the vaccine was initially presented to the public as a two-dose form, which made people think that was all they needed to be protected enough, Furness said.
“This is the mental model that most people had,” he said. “So when we started saying you need a third dose now … [they] he said, “You sold us the idea that there was a two-dose vaccine and I signed, now you’re changing the deal and I don’t like that, I’m leaving.”
The contribution to this lack of enthusiasm to increase was the lifting of vaccine mandates by provincial governments across the country earlier this year, Muhajarine said. Those who cannot enter restaurants or movie theaters because they were not vaccinated, for example, are no longer banned, and proof of vaccination is no longer required.
“Vaccine warrants worked in terms of getting people who are eligible to receive a second dose,” Muhajarine said. “But when governments started withdrawing these public health measures and vaccine warrant measures, I think people really lost that incentive.”
ENCOURAGING CANADIANS TO PROMOTE THEMSELVES
While urging public health authorities to include third doses in the definition of “fully vaccinated,” Furness said more than just changing the definition to encourage people to receive their booster vaccine. Part of the solution lies in the vaccine mandates that are enforced and enforced by employers and governments.
“[If] your employer has forced vaccination and this is changed to three doses, then we will have a meaningful public conversation about what the risk and benefit are, “said Furness.” Once we have enough public conversation, people will start to consider ho … [otherwise] it will seem like just a bureaucratic move. “
Having an open conversation about the role vaccines play in the fight against COVID-19 will be especially helpful for those who are hesitant or afraid to get vaccinated, Furness said. Part of the solution also lies in increasing education about the function of vaccines, as well as improving public health messages and more local engagement, Furness said.
“It simply came to our notice then [group] that’s not sure who to believe, and anyone in that category won’t do anything until you make a good case; that’s where there’s work to be done, ”Furness said.
According to his observations, the appetite for vaccine warrants across Canada is still low at the moment, Muhajarine said. But a scenario in which you could see these rules being reintroduced at the provincial level is if governments see another wave of cases, or if another variant or subvariant emerges, he said. In this situation, it is crucial that officials do not wait too long to act, Muhajarine said.
“Provincial governments have the authority and responsibility to introduce policies that keep their people safe,” he said. “During COVID-19, what we’ve learned is that swift action is really important. We can’t wait until COVID starts to really hurt us to act against it.”
Furness also said that as pharmaceutical companies approach the development of a specific Omicron vaccine, it is likely to encourage more people to receive their third dose if they have not already done so.
“If we can go back and say, ‘Look, the vaccine …