The genetic makeup of the subvariant makes it difficult to detect by monitoring wastewater.
A highly transmissible coronavirus strain dubbed the “Kraken variant” is spreading faster in parts of Canada, according to a new report.
Provincial health officer Dr. Bonnie Henry told reporters at a Jan. 13 briefing that the lion’s share, about 95 percent, of COVID-19 cases in British Columbia are still the BQ.1.1 subvariant. But in Ontario, cases of the XBB.1.5 strain — the Kraken sub-variant — are rising rapidly.
Public Health Ontario predicts the share of XBB.1.5 will increase this week to 22.2 percent of all cases in the province. From the available data from December 25 to December 31, the share of XBB.1.5 is only two percent.
British Columbia surveillance data show that about five to six percent of new cases of COVID-19 are this new subvariant. Although this new subvariant appears to be particularly transmissible, Henry said there is currently no evidence that it causes any more severe disease and that the latest bivalent vaccine appears to be effective against it.
A spokesperson for the Public Health Agency of Canada (PHAC) says the genetic makeup of XBB.1.5 makes it difficult to detect through wastewater monitoring.
Because the subvariant is recombinant—its genome is the product of Omicron strains BA.2.10 and BA.2.75 spliced together—it is harder to detect if it is only circulating at low levels.
However, XBB.1.5 can still be detected in wastewater by scanning for “presence of defining mutations” as well as by locating the pedigrees of the parents.
The Kraken variant of COVID-19 has been found in sewage samples in Canada
PHAC says metagenomic sequencing revealed “an increasing XBB.1.5 signal in municipal wastewater samples collected since mid-December.” So far, 19 cases of the subvariant have been detected using Canadian wastewater samples.
Dr. Sara Otto, a professor in the Department of Zoology at the University of British Columbia, told VIA that the scientists did not see a significant change in symptoms with XBB.1.5, but it did show a “transmission advantage.”
With this advantage, the new subvariant is expected to continue the turnover in variants that have led to “high and relatively persistent levels” of COVID-19 in Canada over the past six months.
People should continue to follow the province’s long-standing advice against COVID-19, such as getting vaccinated at all recommended doses to prevent severe illness.
With files by Glen Korstrom
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