To continue to vaccinate the general population against COVID or not? At the start of 2023, Quebec has not decided on the follow-up to be given to the bivalent vaccine, but everything suggests that the Committee on Immunization of Quebec (CIQ) will not advocate extensive vaccination, but rather action targeting in prioritize vulnerable people who have never been infected.
As cases of COVID-19 surge in the United States, spurred by the arrival of the new XBB.1.5 subvariant — even more contagious than its predecessors — many people are wondering if the immunity conferred by a vaccine (monovalent or bivalent) received in the fall or through an infection will be enough to protect them this winter.
The CIQ, which reports to the National Institute of Public Health of Quebec (INSPQ), should send the government its opinion on vaccination against COVID at the end of next week. It will be up to Quebec to see what action to take and what recommendations to make to Quebecers.
But at the dawn of 2023, several health authorities around the world are still doubtful about the stage that will follow the bivalent vaccine granted three or four months ago. “What are we doing for 2023? This is the question that many are asking. No one has decided yet. One thing is certain, those who received the bivalent vaccine in October in Quebec still have immunity for a long time,” says Dr.r Gaston De Serres, member of the CIQ and medical advisor to the INSPQ.
So, do we need a new dose of vaccine to face the winter? It certainly seems that the current answer is no… for the general population.
The uninfected under the radar
Without revealing what the committee will recommend, Dr.r De Serres says the scientific opinion of the CIQ will be guided by the same data that formed the basis of that of last November.
At that time, the expert committee did not recommend giving the bivalent vaccine to the healthy population, but rather only to people who had never been infected and who were part of risk groups — residents of CHSLDs and RPAs. , people over 60 and people who are immunocompromised or have chronic illnesses, in particular. However, Quebec has nevertheless continued to invite people who have been vaccinated for more than six months to “stay up to date”. “However, the CIQ did not recommend a new dose for the youngest or healthy people already infected. The government still decided to make the vaccine available to everyone,” he says.
Current data demonstrates that healthy people with hybrid immunity (vaccine and infection) do not need an additional dose
From a scientific point of view, the data collected in Quebec among those over 60 years old since the arrival of Omicron show, however, that hybrid immunity (conferred by an infection as well as a monovalent vaccine) still offers very good protection against hospitalizations in the following six to eight months (more than 90%), regardless of the number of doses received (two, three, four or five doses).
“The effectiveness of the vaccines increased between doses because the vaccines were given in a short period of time. But over time, the protection decreases, and our data shows that ultimately, the effectiveness is the same after six months, regardless of the number of doses received,” explains Dr.r From Serres.
It is quite different for people who have never been infected, who benefit from having repeated vaccination if they are in a risk group, adds the expert. In this population, vaccine effectiveness in preventing severe COVID increases from 32% after one dose to 74% after five doses. Important data since, according to the Dr De Serres, up to 50% of people over 60 have never been infected, while 75% of young people have been.
“Current data shows that healthy people with hybrid immunity (vaccine and infection) do not need an additional dose,” he says.
XBB.1.5 and China
But several observers believe that the XBB.1.5 variant, at the origin of the current jump in hospitalizations in the United States, militates in favor of a vaccine revival. Health Minister Christian Dubé described the situation south of the border as “worrying” on Thursday and said he was closely monitoring its development. Others add that the virulence of the epidemic in China, favorable to the emergence of variants capable of thwarting current immunity, also militates in favor of a recall.
“If an emerging variant turns out to be able to circumvent the vaccine … we will not be able to relaunch the vaccine, answers the Dr From Serres. But if the same subvariants are involved, it would make much more sense to increase vaccine coverage for vulnerable people who have never been infected than to offer yet another dose to everyone. There is no point chasing after people for whom the vaccine will not change anything. »
We will have to wait for the opinion of the CIQ to know the precise position it will adopt. But in the end, whatever it is, it will be Quebec that will decide whether or not citizens will be called upon to reach out again.