As of January 4, 2022, the Public Health Agency of Canada (PHAC) confirmed that it is aware of 21 XBB.1.5 subvariant cases in Canada. The newest COVID-19 subvariant known as the XBB.1.5 is the "most transmissible subvariant that's been detected yet," according to Maria Van Kerkhove, the World Health Organization's (WHO) COVID-19 technical lead.