The Omicron BA.2 sub-variant, also dubbed “stealth Omicron,” has been detected in at least 40 countries worldwide.
Labs in countries including Denmark and Norway have reported that the sub-variant has been gaining ground, accounting for nearly half of all COVID cases in the former as of January 20, marking a sharp increase in recent weeks.
In a press release issued last Friday, the U.K.’s Health Security Agency (HSA) said that the Omicron variant sub-lineage known as BA.2 has been designated a variant under investigation by the Agency.
The Agency went on to report that In total, 40 countries have uploaded 8,040 BA.2 sequences to GISAID since 17 November 2021. At this point it is not possible to determine where the sublineage may have originated.
The first sequences were submitted from the Philippines, and most samples have been uploaded from Denmark (6,411). Other countries that have uploaded more than 100 samples are India (530), Sweden (181), and Singapore (127).
Dr Meera Chand, COVID-19 Incident Director at UKHSA, said “It is the nature of viruses to evolve and mutate, so it’s to be expected that we will continue to see new variants emerge as the pandemic goes on. Our continued genomic surveillance allows us to detect them and assess whether they are significant.”
A press release from Denmark’s Statens Serum Institut (SSI) infectious disease research institution last week stated that the subvariant BA.2 accounted for 20% of all covid-19-cases in Denmark in December. And other countries also experience an increase in BA.2 cases: E.g. Great Britain, Norway and Sweden
One notable aspect of BA.2 is that it lacks a genetic characteristic that scientists had used to identify Omicron cases previously -giving credence to its “stealth Omicron” monicker.
However, Cornelius Roemer, a computational biologist at the University of Basel in Switzerland, posted to Twitter that BA.2 is still detectable on PCR tests and branded news reports to the contrary as “totally wrong.”
“Depending on the PCR test used it may not look like BA.1 (the other Omicron). But it will still give a positive result,” he added.