Here's why the COVID-19 vaccination remains an important tool | Coronavirus

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Here's why vaccination against COVID-19 remains an important tool | Coronavirus

Faced with an 8th wave of COVID-19, Canadian authorities are issuing another call for vaccination.

With the arrival of an 8th wave, health authorities and governments this week launched a new call for vaccination, the main tool against COVID-19. They believe that too few Canadians are adequately vaccinated.

According to Health Canada:

  • 12% of Canadians over 5 years old have never been vaccinated;

  • 15.9% received a dose in the last six months;

  • less than 5% of children 0-4 years old received at least one vaccine dose.

Here are four reasons why vaccination remains the most effective tool in the fight against SARS-CoV-2.< /p>

Vaccines continue to be the best way to reduce the risk of severe complications and death. Numerous studies show that since the arrival of the Omicron variant, three doses are required to truly reduce these risks.

A CDC report in the United States revealed that the protection against hospitalization after two doses decreases to 57% after six months, but increases to 90% with a booster dose.

Other CDC data have demonstrated that unvaccinated Americans over age 50 were nearly 45 times more likely to be hospitalized than those who were vaccinated.

According to Health Canada, in August 2022, unvaccinated people were seven times more likely to be hospitalized and eight times more likely to die from COVID-19 than people who received two doses and a booster dose.

COVID-19 Resources Canada, for its part, offers a COVID-19 risk index that shows how much better protected people who are properly vaccinated – regardless of age – are .

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Remember that 27% of Canadians have at least one comorbidity (e.g. diabetes, hypertension, asthma, etc.) that makes them vulnerable to COVID-19.

Who is considered at risk?

  • people aged 60 and over;

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    pregnant women;

  • obese people;

  • persons with asthma, diabetes, high blood pressure, or heart, kidney, liver, or lung disease;

  • immunocompromised people.

Public health authorities have been saying it since the beginning of the vaccination campaign: the best way not to succumb to COVID-19 is to get vaccinated. Moreover, it should be noted that with the proliferation of SARS-CoV-2 variants, the number of drugs available to treat and protect people at risk is decreasing.

In this Currently, only 31% of Canadians aged 60-69 and 51% over the age of 70 have received a dose in the past six months.

If COVID-19 vaccines 19 fail to completely stop the transmission of the virus, they still offer some protection against infection.

According to Canadian researchers, in terms of vaccine efficacy against symptomatic infection with Omicron, two doses had an initial efficacy of 36%. After six months, this protection against infection was almost nil. On the other hand, a third dose increases the vaccine efficacy to 61%.

When doing a quick self-test, authorities recommend taking a sample not only from the nose, but also from the throat and cheeks. This allows the test to be 80% more efficient against the Omicron variant.

Vaccination also partially reduces the risk of developing chronic symptoms of the disease (commonly referred to as long COVID), as several studies have shown, including this recent Danish study, unreviewed by peers, as well as this Italian study, this American study and this British study.

According to the World Health Organization (WHO), between 10% and 20% of infected people (including people with mild symptoms) have one or more symptoms three months after their initial diagnosis.

Health Canada reports that, according to some studies, up to 40% of people who have not been hospitalized for their infection are still reporting symptoms after three months.

One ​​study North American study shows that 6% of infected young people still experience symptoms three months later.

In addition, COVID-19 increases the risk of cardiovascular and neurological complications, dementia, diabetes and chronic respiratory conditions.

It should also be remembered that researchers do not know with certainty what the effect of reinfections is and whether each new infection increases the risk of long-term symptoms.

First, we must note that it is never too late for an unvaccinated person to receive their first dose.

If you have been vaccinated, you need to ask yourself a very simple question: when crank up your last dose?

Immunity conferred by vaccination wanes over time; a booster dose allows the immune system to restore a sufficient level of antibodies to compensate for the drop in immunity.

This is why Health Canada recommends a booster dose no more than six months after the last. In Quebec, it is recommended to get a booster dose after five months.

Why six months? Several studies suggest that longer intervals between doses lead to a better and longer lasting immune response.

For those at risk of severe complications, it is suggested to wait three months or more after a COVID-19 infection before receiving a booster dose.

In children, a COVID-19 vaccine reduces the risk of developing “long COVID” and childhood multisystem inflammatory syndrome (MISI) ).

Pediatric formulas are available for children 6 months to 4 years of age (two doses eight weeks or more apart). Booster doses are not yet available for youth under 5 years of age.

A booster dose is recommended for ages 5 to 17 (5 months after last dose in Ontario ; 6 months in Quebec).

It is estimated that a large proportion of the Canadian population has been infected in the past two years. Does one infection equal one dose? Not necessarily.

Health Canada recommends an interval of three months after infection before receiving another dose of vaccine.

According to studies, the immunity conferred by an infection lasts much less than that provided by a vaccine. Additionally, it is unknown whether this immunity will continue to provide strong protection against certain Omicron sublines.

A recent study from Qatar shows that the immunity conferred by an infection decreases over time and that newer variants are more effective at evading this immunity.

Researchers have shown that a person infected with BA.4 or BA.5 (the variants circulating this summer) and showing symptoms would be more than 75% protected against reinfection with these variants.

However, a person infected with any other prior variant (e.g. a BA.1 infection last winter) would be only 35% protected.

Two bivalent vaccines have been authorized in Canada.

While the starter vaccines continue to offer high levels of protection against severe complications and death, Canadians now have access to two bivalent vaccines for their booster dose. These vaccines are designed to target both the parent virus and certain subvariants of Omicron.

Clinical trial data shows that these vaccines provide slightly greater protection against infection caused by Omicron.

Moderna's vaccine is suitable for the BA.1 subvariant. This variant is no longer circulating in the country, but it is estimated that this bivalent vaccine generated a good immune response against the Omicron BA.4 and BA.5 subvariants, which account for almost all of the COVID-19 cases currently in the country. Canada.

As for Pfizer's vaccine, it targets the BA.4 and BA.5 subvariants.

For now , there is no reason to recommend one bivalent vaccine over another. It is not yet clear whether any of the new circulating subvariants (e.g., B.Q.1.1 and XBB) will successfully evade the immunity conferred by these new vaccines.

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