Is a second dose needed for those who have had COVID-19? | Coronavirus

As a result, a large portion of infected Quebecers did not make an appointment for the second dose, believing they were not eligible.

But in fact, and even if this is not explicitly indicated on the government site, it is already possible for a Quebecer previously infected to receive two doses.

With informed consent, it is possible to receive two doses if desired, says by email the Ministry of Health of Quebec, specifying that for immunosuppressed people who have had COVID-19, two doses are recommended.

Thus, a person who has had COVID-19 will not be refused if they want a second dose of the vaccine; she can come to a walk-in clinic or make an appointment.

Benoit Barbeau, professor in the Department of Biological Sciences at UQAM and specialist in virology, believes that this lack of clarity from the government sends the wrong message to the population.

Quebec is pushing for people to be vaccinated, but someone who has been infected is told that they do not need a second dose. This is not an easy message to understand …, he laments.

Especially since this Quebec approach is starting to become problematic, since several countries, including Canada, indicate that it will be necessary to have proof that one has had two vaccines to travel and avoid quarantine.

So a dose or two?

There is no doubt that a person infected with COVID-19 develops a certain natural immune response against the disease, but there are still some questions as to how long it persists.

There are too many factors that could cause the level of protection to be lower if an infected person does not receive two doses., said Mr. Barbeau.

But it is still difficult to say for sure whether these two doses are really necessary for an infected person, he adds.

According to the pediatrician and microbiologist-infectious disease specialist at CHU Sainte-Justine, Dr. Caroline Quach, the natural immune response following an infection seems to last at least six months. And one dose of the vaccine appears to amplify the immune response enough to provide adequate protection against the disease.

Those who have had COVID-19 and received a first dose are known to have an excellent immune response, similar to that obtained after two doses, says Dr. Quach, who until recently chaired the National Advisory Committee on Immunization (NACI).

Microbiologist-infectious disease specialist and epidemiologist Caroline Quach.

Photo: Radio-Canada / Ivanoh Demers

While, in theory, one infection should protect against a second infection, there are certain factors that need to be taken into consideration, says Barbeau.

For example, if the immune response following an infection seems to last for several months, there is no guarantee that this natural immunity will protect forever, especially against certain variants.

What about people who were infected at the start of the pandemic, more than a year ago? Do they have enough antibodies left? Hard to say, say Dr. Quach and Mr. Barbeau.

In addition, the natural immunity acquired after an infection is not necessarily the same from one person to another, specifies the latter.

The sicker people are when they are infected, the stronger the immune response, he explains. So a person who tested positive, but was asymptomatic, may not have developed enough antibodies and may need a second dose, says Barbeau.

If you think you have been infected, but are not sure, I would not trust this too much. [l’immunité naturelle acquise par l’infection] so as not to take a second dose, he warns.

Given all of these uncertainties, Benoit Barbeau believes it would be wiser to give both doses to people who have been infected.

I think it would be better to go with two doses; protection will be assured.

Dr. Quach also believes that infected people do not have to worry about a second dose and that they can require it, especially if they are thinking of traveling.

The 2nd dose may be futile for some people [qui ont été infectées], but it is not dangerous. We know that those who have been infected and given two doses do not have many more side effects., she argues.

Quebec stands apart

Elsewhere in the country, Canadians who have been infected receive two doses. In fact, NACI also recommends two doses for the more than 1.4 million Canadians previously infected.

In the United States, the CDC also recommends two doses. And in the world, only France and Israel do not give a second dose of the vaccine to people already infected.

Quebec’s decision to take the same path as France had been taken in the wake of the vaccine shortage that occurred in the spring and has since subsided.