As summer approaches and COVID-19 health measures continue to loosen, experts say the rise in Omicron subvariants could lead to a further increase in cases in Canada.
Subvariants BA.4 and BA.5 have been feeding a growing number of cases in the US, Europe and around the world. In Canada, the two variants accounted for 3.9 per cent and 6.5 per cent of COVID-19 cases, respectively, according to samples collected in the week of May 29. The cases of BA.2.12.1, another growing subvariant, also account for 40.5 percent. of cases.
Speaking at a media conference on Friday, Canada’s medical director of health, Dr. Theresa Tam, noted the growth of these subvariants, saying that “they have shown a growth advantage in additional immune escape” over the variants. citing the decline in vaccine immunity and viral evolution.
“We do not expect our progress to be linear, so maintaining preparedness for a potential resurgence that could have a serious impact is our best advantage,” Tam told reporters.
Toronto emergency physician Dr. Kashif Pirzada says the increase in these subvariants shows how quickly the virus can mutate.
“It’s evolving to beat our immunity and our vaccine and it looks like we’ll be in a world where we have waves every two or three months,” he told CTV news channel on Saturday. “The craziest thing is that the immunity of a previous infection, even if you had Omicron in the January wave or during the last month, may not protect you from this variant because it’s different enough for your immunity not strong enough for that. “
In Portugal, where the BA.5 variant accounted for 87% of cases on 30 May, hospitalizations increased as a result. Last week, the Centers for Disease Control and Prevention announced that BA.4 and BA.5 now account for 8.3% and 13.3% of COVID-19 cases in the U.S., respectively.
“If you look at countries like Portugal, which got the BA.5 variant … this is one of the highest vaccination rates in the world and you see an increase in hospitalizations there. So this could be a warning to us. , “Pirzada said. “Hopefully, the summer weather here and the schools being let out now will keep us from going so bad, but it means we have to be careful.”
Dr. Zain Chagla, an associate professor at McMaster University in Hamilton, Ontario, and an infectious disease physician in St. Joseph’s Healthcare Hamilton says it is not yet clear what will happen in Canada.
Portugal, for example, has seen a large wave of BA.4 and BA.5 cases, but had a relatively small number of BA.2 cases, similar to South Africa, it said on Sunday in an email to CTVNews.ca .
But Portugal is also seeing a “decent percentage” of reinfections, and older people appear to be the most likely to get sick, he says.
After taking a maximum of six weeks to reach Portugal, Chagla says another wave of Omicron cases could affect Canada in the coming weeks, with high-capacity, poorly ventilated indoor spaces presenting a higher risk. COVID-19 transmission system.
“At this point people should be committed to what [they] feel comfortable, but recognizing as community rates increase so does exposure in these environments, “Chagla said. environments “.
He recommends that those at high risk for COVID-19 be up to date with their vaccines, including the third and fourth doses. Canadians should also know where and how to get tested if symptoms develop, as well as how to access treatments, which are widely available in Canada and can reduce the risk of COVID-19-related hospitalization.
Canada is currently seeing low rates of cases and hospitalizations, and Tam said the Public Health Agency of Canada is “prudently optimistic about the current trajectory.”
“If you compare where we are now, compared to where we were, you know, a month and two months ago, we’re doing so much better,” infectious disease specialist Dr. Isaac Bogoch told CTV News on Friday.
However, Bogoch believes there may be “a summer blow in the cases, depending on how it develops,” citing wastewater data in Ontario that show a recent rise in SARS-CoV-2 concentrations. .
“It’s showing a slight rise in the signal, and I don’t think it’s just a blink,” he said. “I think it’s the real deal because if you look at the various areas of Ontario and that’s not geographically unique to an area. You’re seeing that sign in a variety of geographic regions.”
With files from CTV National News Toronto correspondent John Vennavally-Rao
Wastewater data in Ontario show a recent increase in SARS-CoV-2 concentrations since early June. (Ontario Science Board)