New immune-evasive strains of highly transmissible Omicron subvariant spread in N.B.

Some offshoots of the COVID-19 Omicron subvariant BA.5 — sparking concern due to their growth advantage and signs of immune evasion — are in New Brunswick and spreading.

The sublineages BQ.1,  BQ.1.1 and  BF.7 represented nearly 27 per cent of the roughly 195 samples sent for sequencing in the past week, according to data provided by the Department of Health.

A combined total of 338 cases have been detected in the province between August and October, but they've never been announced in any of the weekly COVIDWatch reports.

They would have been listed under the umbrella of the highly transmissible BA.5, which has been the dominant strain in New Brunswick for months and represented 94 per cent of the most recent samples sent for sequencing, as of Tuesday's report.

In the United States, BQ.1 and BQ.1.1 have now overtaken BA.5, accounting for an estimated 44 per cent of all new infections, compared to 30 per cent, according to the Centers for Disease Control and Prevention.

The World Health Organization (WHO) has said BQ.1, confirmed in 65 countries and quickly rising in Europe, "warrants close monitoring."

"It is likely that these additional mutations have conferred an immune escape advantage over other circulating Omicron sublineages, and therefore a higher reinfection risk is a possibility that needs further investigation," according to the latest update from WHO's technical advisory group on SARS-CoV-2 virus evolution, or TAG-VE.

"At this time there is no epidemiologic data to suggest an increase in disease severity."

Breakdown of cases

In New Brunswick, there have been 42 cases of BQ.1 detected to date, and it represented eight per cent of the most recent samples, said Department of Health spokesperson Adam Bowie.

BQ.1 was first detected in the province in "mid-October," he said.

BQ.1.1 was also first detected in "mid-October," said Bowie, with a total of 15 cases so far, including roughly 2.5 per cent of the most recent samples.

There have been 281 cases of BF.7 detected since "mid-August," said Bowie. About 16 per cent of the latest samples were BF.7.

If the department determines there is a change of significance, or if there is value in sharing additional information about a certain variant, it may adjust the way it shares its data.- Adam Bowie, Department of Health spokesperson

No additional cases of BA.2.75.2, a sublineage of BA.2, which has mutations that allow it to better evade immunity from vaccination and prior infection, have been detected in New Brunswick, said Bowie. A single case was detected in September, he confirmed to CBC last month.

Asked whether the department is considering providing a more detailed breakdown of subvariants and sublineages, and at what point it might, Bowie replied, "If the department determines there is a change of significance, or if there is value in sharing additional information about a certain variant, it may adjust the way it shares its data."

More subvariants expected

He noted additional variants and subvariants can be expected to be discovered circulating in the future, as the virus continues to evolve.

The COVIDWatch reports provide only a breakdown of the five "major branches" of the Omicron variant — BA.1, BA.2, BA.3, BA.4, and BA.5.

"As we've told you, we're not regularly releasing detailed breakdowns of COVID-19 subvariants, as there have been more than 100 genetic sequences of COVID-19 detected in the province since the beginning of the pandemic," Bowie said in an emailed statement.

The breakdowns provided are meant to "inform the public about the most commonly spreading strains of the virus at any given time," he said.

"I'd like to point out that none of the Atlantic provinces provide as much information in their regular reports as we do about the types of subvariants circulating in their regions," he added.