At least 40 countries have detected this omicron sub-lineage since November 17, 2021
The United Kingdom declared BA.2 a variant under investigation amid an increase in the number of patients infected by the that sub-lineage of the omicron variant of the novel coronavirus. The prevalence of the variant has increased to 426 since it was first isolated in the country December 6. 2021.
At least 40 countries have detected this variant since November 17, 2021. India has reported 530 samples to the Global Initiative on Sharing Avian Influenza Data (GISAID) — the world’s largest database of novel coronavirus genome sequences. The variant has also been found in Denmark, Sweden, Philippines, France, Norway and Singapore.
The designation was based on rising numbers domestically and globally, the United Kingdom Health Security Agency (UKHSA) noted in its latest update from January 21, 2021. “There is still uncertainty around the significance of the changes to the viral genome, and further analyses will now be undertaken.”
So far, there is insufficient evidence to determine whether BA.2 causes more severe illness than Omicron BA.1, said Dr Meera Chand, COVID-19 Incident Director at UKHSA. She added:
We do know that the BA.2 variant does not have the mutation which results in an S-gene target failure (SGTF) during some polymerase chain reaction (PCR) tests — a quick method used widely to detect which variant of the SARS-CoV-2 variant it is since genome sequencing is a time consuming process. This is why it was popularly dubbed as the 'stealth variant' in December when it was first discovered.
The ‘stealth’ variant has 32 mutations in common with BA.1 but also has 28 other mutations, she noted. “It remains to be seen what this means for the virus' virulence and infectivity.”
BA.2 is unlikely to have any severe impact on the ongoing omicron wave, argued Tom Peacock, a virologist at the Imperial College London, in a series of tweets. “Several countries are near, or even past the peak of BA.1 waves. I would be very surprised if BA.2 caused a second wave at this point.”
Even with slightly higher transmissibility, this absolutely is not a delta to omicron change and instead is likely to be slower and more subtle, he said. While BA.1 is now the dominant strain in UK, BA.2 is likely to replace it soon.
The ‘stealth’ version is less likely to evade immunity than omicron to evade immunity, according to predictions by Bloom Lab, a Seattle-based lab studying molecular evolution of proteins and viruses, made in December last year.
Read our coverage of the COVID-19 pandemic here.
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