A sub-lineage of the super-contagious Omicron variant is under investigation by the UK Health Security Agency. However, you can take your finger off the panic button for now: while health authorities clearly believe this strange “sister” of the original Omicron variant is worth keeping an eye on, mutations in a virus are to be expected and don't necessarily spell doom. Known as BA.2, the virus is the “sister” of the original Omicron lineage BA.1. There are clear genetic similarities between BA.2 and BA.1, but also a significant number of different mutations at important sites that make it stand out as its own sub-lineage. According to Statens Serum Institut, the difference between BA.1 and BA.2 is greater than the difference between the original SARS-CoV-2 strain and the Alpha variant. The UK Health Security Agency said in a report published last week that BA.2 does not contain a notable spike deletion that was previously used to identify Omicron cases in PCR tests. Some virologists have pointed out that this may be why BA.2 was initially misdescribed as a “stealth variant” as it was tricky to spot in tests. Cases of BA.2 are on the rise in the UK, Denmark, Norway, and Sweden. In Denmark, it currently makes up almost half of their Omicron cases, after accounting for just 20 percent of cases in the last week of 2021. As of January 10, at least 2,093 cases of BA.2 have been identified worldwide, 53 of which are in the UK, according to the UK Health Security Agency report. There’s currently not enough data to truly know whether this sub-lineage is any more dangerous, deadly, vaccine-resistant, or transmissible than the original BA.1 lineage. Promisingly, initial analysis by the Statens Serum Institut shows no differences in hospitalizations for BA.2 compared to BA.1. Although the sharp rise in BA.2 cases could suggest it’s more transmissible, many scientists appear to believe it's too soon to make any bold assumptions. "Consistent growth across multiple countries is evidence BA.2 may be some degree more transmissible than BA.1," tweeted Tom Peacock, a virologist from Imperial College London. "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 – however we can make some guesses/early observations." Source
