First cases of Delta sublineage AY.4.2 confirmed in British Columbia

Vancouver -

British Columbia has confirmed its first cases of AY.4.2, the descendent of the Delta COVID-19 variant linked to a growing number of infections in the United Kingdom.

Provincial health officer Dr. Bonnie Henry announced the three AY.4.2 cases on Tuesday, noting the sublineage has not yet been categorized as a "variant of concern" and much remains to be known about its effect on the population.

"We are continuing to follow the whole genome sequencing and making sure we're aware of what strains are being transmitted here in British Columbia," Henry said.

All three of the confirmed cases are linked to one family that was exposed at the same time.

AY.4.2 accounted for just over 11 per cent of the U.K.'s Delta cases during the week of Oct. 17, according to the latest available data, but health officials have not determined whether its spread is the result of biological differences.

The B.C. government is also monitoring AY.4.2 to determine whether the descendent causes more severe illness or shows more resistance to the approved COVID-19 vaccines, Henry said.

Early indications out of the U.K. suggest it does not impact the efficacy of vaccines.

B.C. is also continuing to track two other Delta mutations, AY.25 and AY.27, which were first detected in the province back in June and now account for about two-thirds of local cases.

"The strains of the Delta variant that we've seen are spreading much faster and causing more severe illness in younger people, and that remains the same," Henry said. "And our best defence continues to be being vaccinated."

The provincial health officer noted that COVID-19, like any virus, will continue mutating the more opportunities it has to spread to new hosts.

"There are now about 120 different sublineages of the Delta strain of the virus around the world," Henry said.

"Development of these new lineages, which are unique to geographic areas, are really expected over time when we have ongoing transmission in our communities."