The mutation of the Omicron variant was earlier this week classified by the UK Health Security Agency (UKHSA) as under investigation. It said that as of January 10, just 53 sequences of it had been identified in samples.
The news comes as the pandemic appears to be waning in the UK, with cases dropping significantly from a peak early in January – as Omicron took hold and people mixed over the holidays.
However, this evening, Eric Feigl-Ding, an epidemiologist and senior fellow at the Federation of American Scientists, said that the possibility of BA.2 “displacing” the original variant is “a really bad sign”.
He pointed to data which suggested that “almost half” of Omicron cases in Denmark were BA.2 – “surpassing the old Omicron BA.1 variant by a lot.”
Dr Feigl-Ding posted on Twitter: “Either it’s much faster transmission or it evades immunity even more.”
READ MORE: Covid warning as UK detects 53 cases of Omicron sub-variant
He also noted data from Germany, where cases of BA.2 had risen to around 2 percent of Omicron infections by mid-January.
Dr Feigl-Ding commented: “Early but looking exponential too.”
In the Netherlands, Covid statistics suggest that the proportion had reached 5 percent of Omicron cases.
While still early in the UK, Dr Feigl-Ding said that the subvariant appears to be doubling approximately every four days.
However, epidemiologists are still gathering further data to understand whether it is more transmissible than the original Omicron.
On Friday, Dr Meera Chand, UKHSA incident director, said that such subvariants were to be expected as “the nature of viruses [is] to evolve and mutate”.
She added: “Our continued genomic surveillance allows us to detect them and assess whether they are significant.”
According to the latest UKHSA estimates, England’s R number – the rate of reproduction of the virus – is believed to be between 0.8 and 1.1.
This suggests that the pandemic is shrinking slightly or is only growing by a 1 percent increase in cases per day.