L’Organisation mondiale de la santé a d’ailleurs déclaré, au début du mois, que chez les personnes qui s’étaient rétablies, la vaccination ne devait pas être considérée comme « prioritaire ».
Alors, dans un contexte où l’approvisionnement des vaccins est limité au Québec, les personnes qui ont eu la COVID-19 devraient-elles laisser leur dose à quelqu’un d’autre qui ne dispose d’aucune immunité face à la maladie ?
Dans une situation où il serait facile de confirmer qui a eu la maladie et à quel moment, il pourrait être préférable de privilégier la vaccination de personnes qui n’ont aucune protection, croit le Dr Quoc Nguyen, gériatre au CHUM. « Mais dans les faits, c’est très difficile de savoir qui a eu la maladie et depuis combien de temps. »
Mais si quelqu’un a attrapé la COVID-19 au printemps dernier, on suggère qu’elle soit vaccinée. C’est possible que ces personnes-là aient encore une bonne protection, mais pour toutes sortes de considérations logistiques, elles vont le recevoir quand même.
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Dr Gaston De Serres, qui siège au Comité sur l’immunisation de l’Institut national de santé publique
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« Les vaccins de Pfizer ne sont pas faciles à déplacer, il faut distribuer plusieurs vaccins à un même endroit », rappelle le Dr Gaston De Serres. « Si quelqu’un ne se fait pas vacciner maintenant, mais qu’il doit se faire vacciner dans deux mois, c’est compliqué [à gérer]. »For the Dr Nguyen, the urgency of the situation does not allow us to run any risks. “In CHSLDs, due to logistical constraints, we chose to consider that everyone should be vaccinated. ”
Protected naturally… to what extent?
While scientific data is beginning to tell us more about the duration and strength of acquired immunity after having COVID-19, several as yet unknown elements prompt Dr Nguyen to promote vaccination in all elderly people, whether they have contracted the virus or not. The immune response varies in particular depending on the age of the individual. With older people who have recovered from COVID-19, “it’s more difficult to determine the immune response that will follow,” says Dr.r Quoc Nguyen. “It’s different with immunity with vaccination, where the dose is known and the immune response is well characterized. ”
“But I know healthcare workers who are like, ‘I’ve had COVID, maybe I don’t need to be among the first to get vaccinated since I have natural immunity,'” says the Dr Nguyen.
In a study published this week in the British Journal of Medicine, researchers following cohorts of British healthcare workers determined that 83% of those who had been infected with the coronavirus had natural immunity. “There are still 17% who do not have it,” observes virologist Andrés Finzi, of the University of Montreal.
How do we know if our natural protection is sufficient or not? We can’t know.
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Andrés Finzi, virologist from the University of Montreal
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Hence the recommendation, says Finzi, to be safe and to get vaccinated when the opportunity arises.
There is also no contraindication to receiving the vaccine when you have had COVID-19, says Andrés Finzi. Does the vaccine extend the duration and effectiveness of natural immunity? “This is an excellent question to which we do not have the answer yet,” says the virologist, who himself has observed patients recovered from COVID-19 at the very beginning of the pandemic who still enjoy immunity after eight months. The researcher is also leading a project that compares the vaccine response between vaccinated people who had already contracted the disease and those who did not.
– With Alice Girard-Bossé, Press
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