As of Monday, the Public Health Agency of Canada (PHAC) has confirmed up to 42 new cases of the new COVID-19 subvariant, known as XBB.1.5, or “Kraken.†It’s a high leap from the 21 cases reported last week.

Detections are a result of genome sequencing from positive PCR tests received from provinces and territories on a weekly basis.

The new COVID-19 strain has rapidly spread throughout the United States, and the World Health Organization recently called it the most “transmissible subvariant that has been detected yet.â€

The subvariant is a “recombinant†– meaning that its genome result of two strains spliced together. The complex biological structure of this strain fusion makes detection increasingly difficult for researchers.

“Government of Canada scientists are also using wastewater metagenomics sequencing to detect variants of concern, and other important or emerging variants,†PHAC wrote in an email to CTVNews.ca on Thursday. “PHAC’s National Microbiology Laboratory has created capacity to conduct wastewater-based sequencing of SARS-CoV-2 from multiple locations across Canada.â€

Recombinants such as XBB.1.5 can complicate its detection in wastewater if it is circulating only at low levels, PHAC explained.

Metagenomic sequencing, a method that enables researchers to comprehensively sample all genes in an organism present in a sample, is revealing a low presence of XBB.1.5 in municipal wastewater samples, PHAC explained.

PHAC says the same old safety measures apply to any new subvariants.

“Staying up to date with COVID-19 vaccinations continues to be one of the most effective ways to protect against seriousness illness, hospitalization, and death from COVID-19,†PHAC said in the email.

“Individual public health measures are effective actions you can take every day to help reduce the spread of COVID-19. They include things like staying home when sick, properly wearing a well-fitted respirator or mask, improving indoor ventilation and practising respiratory etiquette and hand hygiene.â€

The health agency added that, “These measures are most effective when layered together.â€