As Quebec abandons the mask, a fight is engaged between three more transmissible subvariants that are rapidly gaining ground in the United States and Europe. These newcomers will hit here sooner or later, but it’s hard to say when and who will win the race.
Since Saturday, Quebecers no longer have the obligation to wear the mask. In the short term, this easing may not have too much impact on the number of infections, several experts believe – but only if the weather remains favorable to the decline of the virus and that new variants do not come to play spoilsports.
Because all eyes are currently riveted on new players who are taking the lead in our American neighbors and in Europe, where they have just been declared “worrying variants”.
This is particularly the case of the BA.2.12.1 variant, the youngest of the BA.2 lineage, which largely dominates in several New England states. “It’s hard to say if it will be the summer 2022 or fall variant. Warm weather could delay its spread. But the season in which it will strike will be decisive for its development and for our health system, ”says the Dr Don Vinh, microbiologist and infectious disease specialist at the McGill University Health Center (MUHC).
This sub-variant, 23 to 27% more transmissible than BA.2 (which was already 30% more transmissible than BA.1), also comes from the Omicron line.
If the warm weather manages to slow its progress in Quebec, it could be the star of the fall, when the transmission will be more sustained, adds the Dr Vinh. “It all depends on the weather and how people behave. It’s impossible to know what will happen by then. »
At the same time, in Europe, the BA.4 and BA.5 sub-variants are rising in rank. The European Center for Disease Prevention and Control (ECDC) declared them “worrying variants” on May 12. 10 to 15% more transmissible than BA.2, these two subvariants detected for the first time in January and February 2022 in South Africa will be predominant (for BA.5) in a few days in Portugal, with an increase in 13% cases per day since the beginning of May.
The increases in cases of infection and the rate of positivity observed in this country, combined with the presence in these subvariants of additional mutations facilitating transmission and an ability to evade vaccines and recent infections, were enough to hoist these two newcomers to the select club of variants that the World Health Organization (WHO) worries about.
“What happens in Europe often precedes what will happen here by a few weeks. But being spared BA.5 wouldn’t necessarily be good news if the even more infectious BA.2.12.1 takes over. It could be our next problem, ”says the Dr Vinh.
According to the Dr Gaston De Serres, medical advisor at the National Institute of Public Health of Quebec (INSPQ), no one can say which subvariant will dominate in Quebec over the next few weeks or months. “But when a sub-variant takes over elsewhere, it often does here. What we observe elsewhere, we can think that it will happen here. »
On the other hand, the risk of these new variants causing a next wave will depend on the number of people who were exposed to SARS-CoV-2 during the recent fifth and sixth waves. “What just happened offers a certain level of protection to a large part of the population, in addition to the immunity conferred by vaccines,” he says.
Ever more contagious
According to Alain Lamarre, full professor at the National Institute for Health Research (INRS), the emergence of new variants with an increased potential for contagiousness is limitless.
“The first variant detected in Wuhan had a reproduction factor (R0) of 2 to 3. We have reached a factor of around 12 for BA.2: which means that one person can infect 12 others. But with vaccines and recent infections, the actual reproduction factor in Quebec is actually lower, probably around 1,” he says.
The recent descendants of Omicron (BA.2.12.2, BA.4 and BA.5) are now among the most contagious known infectious agents, alongside measles (R0 18), pertussis and tuberculosis, explains this expert. Chicken pox has an R0 of 10 to 12; rubella and diphtheria, 5 to 7; and that of influenza or the common cold barely exceeds 1.8 to 3.
According to the Dr Vinh, the government should already be planning a plan B in the event of a sudden increase in cases fueled by the arrival of these new sub-variants. “But our main problem is the weakness of our health system, and that cannot be resolved quickly. So why take off the bandage [le masque] now, when our system is already bleeding? »
According to Anne Gatignol, professor of virology in the Department of Microbiology and Immunology at McGill University, dropping the mask now increases the risk of contagion. “But it is not because it is no longer mandatory that it must be removed at all costs. Good weather helps, but people will also travel and expose themselves more. We must remain vigilant, get vaccinated. Which variant will take over? Impossible to say. But I would keep the masks not too far away! »