The UK Health Safety Agency has called a subline of the highly transmissible Omicron variant under investigation, saying it may have a growth advantage.

BA.2, which does not have the specific mutation observed in Omicron that may help distinguish it easily from Delta, is being studied but has not been identified as a variant of concern.

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“It is in the nature of viruses to evolve and mutate, so it can be expected that new variants will continue to emerge,” said Dr. Meera Chand, Incident Director at the UKHSA.

“Our continuous genomic monitoring allows us to detect them and assess whether they are significant.”

The UK has sequenced 426 cases of the BA.2 subline, and the UKHSA said that while there was uncertainty about the significance of the changes to the viral genome, early analysis indicated an increased growth rate compared to the original Omicron lineage BA .1.

According to the UKHSA, 40 countries have reported BA.2 sequences, with most samples reported in Denmark, followed by India, the UK, Sweden and Singapore.

In Denmark, BA.2 has been growing rapidly – accounting for 20 percent of all COVID-19 cases in the last week of 2021 and rising to 45 percent in the second week of 2022.