“As of April 6, 2022, the Public Health Agency of Canada (PHAC) is aware of six detections of the XE recombinant lineage of Omicron in Canada,” a PHAC spokesperson wrote in an email.
COVID-19 XE is a recombination of Omicron’s BA.1 and BA.2 subvariants. A recombinant virus is a combination of genetic material from two or more different viruses, in this case, the original variant of Omicron and the more infectious “stealth Omicron.”
The XE recombinant variant was first detected in the U.K. in mid-January, and there have been 637 cases identified in the country since then. Limited cases have also been reported in China and Thailand. The locations of the XE COVID-19 infections, or how infections happened, were not disclosed.
“This particular recombinant, XE, has shown a variable growth rate, and we cannot yet confirm whether it has a true growth advantage,” said Prof. Susan Hopkins, chief medical adviser for the U.K. Health Security Agency.
The World Health Organization (WHO), though, said the variant is believed to be 10 per cent more transmissible than the BA.2 variant.
Recombinant viruses are a fairly common occurrence, especially when there are multiple variants in circulation, according to Hopkins. She noted that recombinants have been discovered throughout the pandemic and similar to other variants, they tend to die off quickly.
While provinces and territories have reduced or entirely removed COVID-19 measures, the federal government’s monitoring program remains in place to identify different variants of COVID-19. In February 2021, the government of Canada invested $53 million into a Variants of Concern Strategy aimed at scaling up surveillance, sequencing and better detection variants.
“Scientists from the Public Health Agency of Canada (PHAC), along with national and international experts, are actively monitoring and evaluating this recombinant sub-lineage and the associated studies,” said a PHAC spokesperson.
The spokesperson confirmed that the agency is looking at signs that “XE changes disease severity, transmissibility or impacts the effectiveness of diagnostic tests, vaccines or treatments for COVID-19.” They noted the WHO’s finding that the variant is more transmissible, but noted that more data is needed to confirm transmissibility levels.
— with files from Reuters