A new form of Omicron named BA.2 has been deemed a “variant under investigation” with more than 100 confirmed cases in London, the UK Health Security Agency has said.
There have been 426 cases cases of the sub-lineage identified in the UK, the agency said in a statement on Friday.
The areas with the largest number of confirmed cases are London (146) and the South East (97).
There is no early indication that the subvariant is more severe than Omicron. Initial studies from Denmark, where it constitutes around half of all Omicron cases, show no increased risk of hospitalisation.
There is some evidence the variant is more transmissable. The UKHSA said early analyses suggest an increased growth rate compared to the original Omicron strain BA.1.
However growth rates have a low level of certainty early in the emergence of a variant and further analysis is needed, it said.
There is still uncertainty around the significance of the changes to the viral genome, and further analyses will now be undertaken.
Dr Meera Chand, incident director at the 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.
“Our continued genomic surveillance allows us to detect them and assess whether they are significant.”
Dr Tom Peacock, a virologist at Imperial College London, also confirmed there is some evidence that the sub-lineage could be more transmissible than BA, the original variant, which is spreading rapidly across the globe.
He said: “Consistent growth across multiple countries is evidence BA.2 may be some degree more transmissible than BA.1.
“Unfortunately this is really where the evidence mostly ends. We do not currently have a strong handle on antigenicity, severity or a much evidence for how much more transmissibility BA.2 might have over BA.1 .”
Denmark’s Statens Serum Institut, a government-run infectious disease research center, said on Thursday: “Initial analysis shows no differences in hospitalisations for BA.2 compared to BA.1.
“Analyses regarding infectiousness and vaccine efficiency etc. are ongoing, including attempts to cultivate BA.2 in order to perform antibody neutralization studies. It is expected that vaccines also have an effect against severe illness upon BA.2 infection”.
