The UK Health Security Agency has designated the Omicron variant sub-lineage, known as BA.2, as a variant under investigation – but current case rates are very low.
Just 53 sequences had been identified in the UK by 10 January, according to the UKHSA, which said it was doing further analysis.
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.
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Vaccines are also expected to be effective against BA.2 in fighting severe illness, according to Danish health officials.
Advertisement 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”.
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Related Topics: COVID-19 Coronavirus Omicron “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.
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.
Some 2,093 sequences of BA.2 had been recorded on an online database from 22 countries – including the UK, the UKHSA said last week.
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”.
“It is expected that vaccines also have an effect against severe illness upon BA.2 infection,” it added.
Some experts have said it’s possible the sub-lineage could spread quicker than ‘original’ Omicron.
Analysis: Something to keep an eye on – but no cause for panic Tom Clarke Science and technology editor
@aTomClarke Could the timing be any worse? A new “sub-lineage” of Omicron coming along just as the government abandons all COVID restrictions.
But while BA.2.is definitely something to be keeping an eye on, it’s not one to worry about too much based on what we know so far.
BA.2 has been circulating in the UK for some time at a low level compared with the dominant type of Omicron here (BA.1).
In parts of India and the Philippines it is the major version of Omicron.In previous waves there have been big regional differences in what sub-lineage of a particular variant is more, or less dominant.
The reason it’s been elevated to a “variant under investigation” is because of what’s happening in Denmark.
Yesterday, Danish officials announced the BA.2 sub-lineage now accounted for nearly 50% of cases in Denmark (up from just 20% at Christmas).
What’s more, the BA.1.
version of Omicron and the Delta variant are on their way down in the country.Denmark also finds itself in a spectacular surge in COVID-19 cases.
It’s good evidence, though not proof, that the BA.2.might be more infectious than BA.1.
The question scientists in Denmark are trying to answer is whether case numbers are surging there because of the BA.2 lineage or would have done whichever flavour of Omicron it might be.
The feeling among virologists is that BA.2 can’t be that much more infectious than BA.1 because if it was, we’d likely have seen it rapidly replace BA.1.
in places like the UK.Yet we’ve seen a very small number of cases.
For that reason it’s unlikely to lead to a significant new wave of cases here – the difference between Omicron BA.1.and BA.2.
is nothing like the difference between Delta and Omicron.
Another reason we shouldn’t be too concerned is that evidence from Denmark and India shows no evidence of increased severity of illness with BA.2 compared to BA.1.
And while BA.1 is genetically different from BA.2, it is not anticipated it will be much better at avoiding antibodies from vaccines or previous infections.
The worst that might happen is BA.2 gradually replaces BA.1 in the UK and makes the downward slope of our Omicron wave that little bit longer.
But if COVID-19 has taught us anything it’s to assume nothing and wait for the evidence.So watch this space.
“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 much evidence for how much more transmissibility BA.2 might have over BA.1 – however we can make some guesses/early observations.”
Big drop in England’s R value
As coronavirus cases fall in the UK, England’s R number range has dropped significantly in the latest UKHSA estimates, moving from 1.1-1.5 to 0.8-1.1.
This suggests the pandemic is shrinking or staying roughly level.
A value between 0.8 and 1.1 means that, on average, every 10 people infected will infect between 8 and 11 others.
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Doctor: Scrapping Plan B rules is ‘terrible timing’ The lowest range was in London, at 0.7-0.9, the highest in Yorkshire and the North East, at 0.8-1.2.
Meanwhile, latest data from the Office for National Statistics (ONS) show decreases in people testing positive for COVID in most of the UK nations in the week ending 15 January.
Around one in 20 are estimated to have had the virus in England, one in 25 in Wales, and one in 20 in Scotland.
Northern Ireland showed an increase in the two weeks to 15 January, also with an estimated one in 20 infected, but the ONS added the trend in the latest week was “uncertain”.
Related Topics COVID-19 Coronavirus Omicron.