COVID-19 vaccine: additional and booster dose

This health tip was made possible with the support of Moderna, without any right of review on the content.

Are you vaccinated against COVID-19 and wondering about the need for an additional dose? Here's some information on the subject.


Why an extra dose of the vaccine?

The fight against COVID-19 is one that everyone wants to win as soon as possible! Fortunately, humanity can count on a major weapon against this virus: vaccination. If you have already received your doses of vaccine, you have made a great contribution to this collective war effort!

On the other hand, the coronavirus has an important asset: genetic mutation. Viruses are living organisms that, like humans, seek to reproduce to ensure their survival and advancement. Unlike us, viruses do not need a sexual partner to multiply; instead they use replication. During this process, they have the ability to mutate, that is, to change their genetic information. Unfortunately, this fascinating phenomenon of biodiversity can sometimes give us a hard time, as in the case of the coronavirus!

In order for mutation to occur, a virus must first infect a human cell. Each time it infects a new person, this gives it the opportunity to mutate. As more people become infected, the virus has a better chance of changing and adapting.

In order to fight the spread of variants such as Omicron, many countries around the world have decided to use additional doses of the COVID-19 vaccine.

In Canada, based on the current epidemiological picture and available scientific data, there are recommendations for an additional dose of the COVID-19 vaccine, as well as a booster dose, to provide further protection against the coronavirus and its variants.


What is the difference between an additional dose and a booster dose?

An additional dose may be required for certain groups of people who may have a lower response to vaccination or whose immune systems produce fewer antibodies. This additional dose maximizes protection against COVID-19 for these more vulnerable individuals. Therefore, their full vaccination schedule includes an additional dose.

A booster dose is recommended for anyone with a normal response to vaccination to compensate for the drop in antibodies that naturally occurs a few months after completing the basic vaccination. The booster dose not only prolongs, but also enhances immunity to COVID-19. 


Who should receive an additional dose of the COVID-19 vaccine?

To protect against the virus and its variants, some individuals who are more susceptible to complications from COVID-19 may benefit from an additional dose of a messenger RNA vaccine, such as the Pfizer and Moderna vaccines. This third dose should be given at least four weeks after the second dose, especially in individuals who:

  • have a compromised immune system due to treatment (e.g. radiation or chemotherapy), certain medications, or HIV (if the person is not consistent with their treatment or if their CD4 cell count is below 500/mm3)
  • are on dialysis

These recommendations may change over time. For full details on the additional dose, consult this hyperlink.


Who should receive a booster dose of the COVID-19 vaccine?

Although the full vaccination schedule offers some protection, the booster dose provides additional protection to reduce the number of cases and the risk of complications. An interval of three months or more is required between the last dose of the vaccine received and this booster dose.

Recommendations may change over time. For full details on the booster dose, check out this hyperlink


How to receive your extra dose of the vaccine ?

If you live in a private seniors' center or residence (PSR), ask your care team about vaccination in that location. In most cases, it is possible to benefit from the presence of a mobile clinic, which provides easy access to the vaccine.

It is also possible to receive a COVID-19 messenger RNA vaccine at the pharmacy, regardless of the vaccine you received for your previous doses. To make an appointment, please follow this link:

It is important to follow public health recommendations for vaccination. Since the data is constantly changing, consult your pharmacist, who will make sure to follow these recommendations and suggest the best time to complete your vaccination.

If you have any questions about COVID-19 or vaccination, or any other health-related question, your Jean Coutu affiliated pharmacist is a valuable ally. Do not hesitate to consult them.


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COVID-19 vaccine: additional and booster dose

Are you vaccinated against COVID-19 and wondering about the need for an additional dose? Here's some information on the subject.
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