All N.B. COVID-19 cases now Omicron, 'almost exclusively' BA.2 subvariant

Omicron is now the only strain of COVID-19 circulating in New Brunswick, and almost all of the cases are the highly transmissible subvariant BA.2, according to the Department of Health.

No cases of the newer, even more infectious Omicron subvariant XE, which is a combination of BA.2 and BA.1, have been detected yet, says the province's acting deputy chief medical officer of health.

But the province continues to conduct typing of random positive cases to determine what kind of variants are spreading across the province, said Dr. Yves Léger.

"We know that the pandemic is a global event and that, as we have seen so far, we will continue to see new variants that will appear."

As the virus continues to spread, it adapts and changes, said Léger.

"Certainly we always hope that [the new variants] will not necessarily be more transmissible or certainly … cause more severe disease," he said.

"But we will continue to monitor that very closely and make sure that we have both the capacity to detect it and to test for it in the province."

BA.2 is the dominant subvariant globally, representing nearly 94 per cent of all sequenced cases, according to the World Health Organization. 

It was first confirmed in the Moncton region, Zone 1, in February.

Early research suggests BA.2 is five to seven times more transmissible than the original COVID-19 strain first detected in Wuhan, China, or roughly two times more transmissible than the Delta variant, which first hit in late 2020 and early 2021.

But so far, the evidence suggests it is no more likely to cause severe disease.

"What we've seen here certainly in the last week or two is, is almost exclusively BA.2," said Léger.

The growth of the subvariant in the province underscores the need for people to get vaccinated and get their third dose if they haven't already, he said.

XE, which was first detected in the United Kingdom on Jan.19, is 10 per cent more transmissible than BA.2, which is 60 per cent more transmissible than BA.1, officials have said.

WHO is also tracking other Omicron subvariants, including BA.1.1, BA.3 and, more recently, BA.4 and BA.5, to assess whether they're more infectious or dangerous.

Omicron tripled Canada's infection count, study finds

The number of Canadian adults infected with COVID-19 during the Omicron-fuelled fifth wave of the pandemic tripled, compared to the previous four waves, according to a recent study led by Toronto researchers.

Nearly 30 per cent of adults — roughly nine million people — were infected during the first Omicron wave of infections (BA.1) earlier this year, compared to just 10 per cent during the previous four waves, the Action to Beat Coronavirus (Ab-C) study found.

Of those nine million infections, nearly one million were among the country's 2.3 million unvaccinated adult population, representing 40 per cent of all unvaccinated adults, the findings, published in a letter to the editor in The New England Journal of Medicine Wednesday, show.

"If we take into account the fact that pediatric surveys have estimated that the proportion of infections among children was as high or higher than it was among adults and that new subvariants of Omicron continue to infect Canadians in the ongoing sixth wave, there are now millions more infections to add to the Ab-C study's total," Catherine Hankins, co-chair of Canda's COVID-19 Immunity Task Force, said in a news release.

"In short, a substantial portion of the Canadian population now has hybrid immunity — defined as a combination of a past COVID-19 infection along with between one and three doses of a COVID-19 vaccine."

Every dose of vaccine and previous infection boosted immune responses, according to the study, a collaboration between Unity Health Toronto, the University of Toronto's Dalla Lana School of Public Health, the Angus Reid Institute and the Lunenfeld-Tanenbaum Research Institute at Sinai Health.

Canadian adults with three vaccine doses and a past infection from COVID-19 had the highest protection, it found.

The study was conducted using blood samples from more than 5,000 Canadian adults between Jan. 15 and March 15.

Researchers have already started the next phase of the study, which involves the subvariant BA.2. They are surveying roughly 1,300 Canadian adults who were not infected by the initial Omicron variant BA.1 to determine whether they were infected by BA.2 between March and June.

Ab-C has been tracking the pandemic in Canada through blood sample collection and periodic polling about lived experience since May 2020. It is funded by the federal government through its COVID-19 Immunity Task Force.