At the start of the summer holidays, COVID-19 is still part of the landscape, but in a new form once again. The number of cases has started to rise again, and new variants are appearing. State of play.
What is the state of the situation in Quebec?
In Quebec, the Omicron BA.2.12.1 subvariant dominates, but the BA.4 and BA.5 variants are progressing, according to data updated on June 22 on the site of the National Institute of Public Health of Quebec. Quebec (INSPQ). “People travel a lot, and those returning from Europe arrive with COVID-19,” explains epidemiologist Nimâ Machouf. “It’s a shame that the mask is no longer compulsory in public transport,” she adds.
The Dr Don Vinh, a microbiologist-infectious disease specialist at the McGill University Health Center (MUHC), observes that, since the beginning of June, the hospitalization rate has reached a stable plateau of around 1,000 beds associated with COVID-19, but that begins to increase slightly. “The number of people entering hospital with COVID-19 is growing faster than the number leaving. This means that there is something, probably the introduction of new variants, which is slowing down the descent”, he explains.
BA.4 and BA.5 are taking over in Quebec, adds Alain Lamarre, virology expert at the National Institute for Scientific Research (INRS), but do not expect a huge wave this summer.
What are the characteristics of BA.4 and BA.5?
The Omicron BA.4 and BA.5 variants were identified a few months ago and are similar to BA.2, explains Benoit Barbeau, virologist and professor in the Department of Biological Sciences at UQAM. “There are changes that probably make them more transmissible, based on what you see in the field,” he explains. Both variants have a particular ability to circumvent immunity acquired by previous infection or vaccine doses.
“We don’t believe they are more dangerous,” he adds. It’s part of the Omicron group, and there’s some convergence between the variants and the sub-variants in terms of their impact on the health of infected people. »
Is it better to wait for more effective vaccines?
Expect a bigger spike in cases after the summer, and more effective versions of messenger RNA vaccines will hit the market probably this fall. Is it better to take a booster dose right away, or to wait?
“If we are eligible for a booster dose immediately, we should go now, even if it means taking another this fall,” said Alain Lamarre of INRS.
Moderna is the most advanced with a so-called “bivalent” vaccine, which targets both the original strain of the virus and that of Omicron BA.1. Clinical studies of this vaccine so far indicate more effective results in neutralizing infections.
It is better to take your first booster dose, thinks Benoit Barbeau, but the second [quatrième dose] “didn’t really show as much efficacy as the first booster dose,” he says, referring to an Israeli study.
According to him, it is better to wait for the arrival of more effective vaccines, unless the person is at risk. “For the vast majority of people who have had their booster dose, waiting until the fall is the best strategy because it will be a more favorable time for transmission, and we will know more about the vaccine options available. »
What does wastewater reveal?
The INSPQ published data last week analyzing the presence of SARS-CoV-2 in wastewater from Montreal, Laval, Quebec City and Gatineau. Since access to PCR testing is restricted in the province, this method can detect the virus in the stools of sick people, including those who are asymptomatic or have not been tested.
In Montreal, the quantity of SARS-CoV-2 has reached a record level in recent weeks since April 15 at a treatment plant in the south of the city. The latest data shows a rapid and marked drop in the concentration of COVID-19 between June 12 and 15 in Quebec City, after reaching an increasing peak since the end of May. In Laval, the quantity of virus detected has gradually increased since June 7 in two stations, but has rapidly decreased since June 12 in the third. In Gatineau, the concentration began to increase on June 5 and then stabilized a week later.
“What we see in the wastewater is that the virus is still circulating and that there is more circulation than in May, underlines Dominic Frigon, professor of civil engineering at McGill University and one wastewater analysis project coordinators. But it hasn’t started again like at the end of 2021 and the beginning of 2022. We are in a more stable situation, there are wavelets at the moment. »