A new form of Omicron named BA.2 has been designated a "variant under investigation", with 426 cases of the COVID-19 strain's sub-lineage confirmed in Britain, the UK Health Security Agency (UKHSA) said.
"Overall, the original Omicron lineage, BA.1, is dominant in the UK and the proportion of BA.2 cases is currently low," with the earliest dated December 6, 2021, Xinhua news agency quoted the UKHSA as saying in a statement on Friday.
In total, 40 countries have uploaded 8,040 BA.2 sequences to the Global Initiative on Sharing All Influenza Data (GISAID) since November 17, 2021 and at this point, it is not possible to determine where the sub-lineage may have originated, it said.
The first sequences were submitted from the Philippines, and most samples have been uploaded from Denmark (6,411), while other countries that have uploaded more than 100 samples are India (530), Sweden (181), and Singapore (127), according to the UKHSA.
Meera Chand, incident director at the agency, said new mutations are "expected" as the pandemic continues.
"So far, there is insufficient evidence to determine whether BA.2 causes more severe illness than Omicron BA.1, but data is limited and UKHSA continues to investigate."