Health officials say they've detected at least 15 cases of the COVID-19 Omicron subvariant BA.2 in Ontario.

Public Health Ontario released the latest data on Friday afternoon, saying that eight of the cases were identified between Jan. 1, 2021 and Dec. 11, 2021, while the seven remaining cases were found between Dec. 12, 2021 and Jan. 8, 2022.

BA.2 is a descendant of the highly transmissible Omicron variant and has been found in at least 40 countries so far. It was first detected in November last year.

While the World Health Organization (WHO) has not yet dubbed BA.2 a "variant of concern," it is tracking its spread.

The subvariant is widely considered stealthier than the original version because particular genetic traits make it somewhat harder to detect. Some scientists have expressed worry that it could also be more contagious.

It is not yet clear whether it evades vaccines better or causes more severe disease.

The Omicron variant, B.1.1.529, has four sub-lineages: BA.1, BA.1.1, BA.2 and BA.3.

Seven of the 15 cases in Ontario are from Toronto. Public Health Ontario did not identify the location of the remaining eight cases.