Thread by @DrEricDing

📍NEW “BA2” SUB-VARIANT—@UKHSA has designated a #Omicron sub-lineage, known as BA.2, as a new “variant under investigation”. 53 in 🇬🇧 but 2,093 sequences of BA.2 recorded from 22 countries. Unclear yet—but “possibility it could be more transmissible.” 🧵
news.sky.com/story/amp/omic…

2) “Initial studies from Denmark - where it's quickly taken hold and now makes up around half of Omicron cases - show no difference in hospitalisations between 'original' Omicron and BA.2. Vaccines also expected to be effective against BA.2 in fighting severe illness, says 🇩🇰

3) “However, more data is needed to test whether it could be even more transmissible.
The UKHSA's incident director, Dr Meera Chand, said the altered form of Omicron was not unexpected as it is "the nature of viruses to evolve and mutate".

4) "Our continued genomic surveillance allows us to detect them and assess whether they are significant," added Dr Chand.

BA.2 is S-gene positive - which may make it **harder to show up** 👀 as Omicron than BA.1, which accounts for 99% of cases.

5) S-gene target failure helps identify Omicron and can be picked up in PCR tests because as a rule Delta cases have the S-gene and Omicron cases don't.

6) Denmark's Statens Serum Institut, part of its ministry of health, has said hospitalisations appear to show no difference for the two Omicron lineages but that "analyses regarding infectiousness and vaccine efficiency etc. are ongoing".

en.ssi.dk/news/news/2022…

7) Some experts have said it's possible the sub-lineage could spread quicker than 'original' Omicron.

8) "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.

9) The subvariant #BA2 accounted for 20% of all covid-19-cases in Denmark in week 52 increasing to approximately **45% in week 2**. During the same period, the relative frequency of BA.1 has dropped. en.ssi.dk/news/news/2022…