Nearly 1,000 cases of a new Omicron COVID-19 subvariant dubbed BA.2.20 have been detected in Ontario since mid-February, and it may have a small growth advantage over the currently dominant lineage in the province.
Public Health Ontario says the new subvariant “had increased circulation, particularly in Ontario and in some American states,” according to a report quietly released Monday.
A second major iteration of the Omicron variant, known as BA.2, is now dominating the province as the sixth wave of the pandemic subsides.
This new Ontario-specific subvariant has two mutations that distinguish it from BA.2, but the exact effects of the mutations are not yet known.
“Currently, the impact of these mutations on transmission, risk of serious disease, reinfection and breakthrough infection are unknown,” Public Health Ontario scientists wrote in their report released earlier this week.
So far, 996 cases of the subvariant have been found in the province.
An analysis of the BA.2.20 cases found so far suggested that the new subvariant could be associated with a growth advantage of up to 24 percent over the dominant BA.2 strain, but they assessed this finding with a low level of confidence.
Epidemiologists say the first case of this new Ontario subvariant was discovered in London, Ontario. on February 14, 2022.
She received a formal Pango line designation back in April, confirming her as unique.
Its world’s earliest known specimen was also found somewhere in Canada in January.
The proportion of BA.2.20 cases has increased in Ontario from less than one percent in early March to six to seven percent in mid-to-late April.
It was most commonly found in Toronto, the broader GTHA and London, mainly in young adults aged 20 to 39.
85 percent of the known cases were in people who had received two or three doses of the COVID-19 vaccine.
Only 19 of the 996 examples known to Public Health Ontario to date were discovered through border testing of incoming air and land travelers.
Three percent (30) of the cases identified to date required hospitalization, which is approximately in line with Omicron’s observed hospitalization rates since March.
As of April 20, no deaths due to infection with BA.2.20 have been observed.
Since April, 10 percent of all COVID-19 cases confirmed in Ontario have been referred for full genome sequencing, up from 50 percent of all cases detected in March.
New subvariants of COVID-19 strains are regularly emerging around the world, but this is the first time such a subvariant has appeared so concentrated in Ontario.
Public health officials use a lengthy laboratory-based process known as full genome sequencing to map the unique characteristics of the coronavirus as it evolves to identify the level of risk posed by the changes.