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 to 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.

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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.

Omicron 'sub-lineage' BA.2 designated as COVID variant under investigation, says UKHSA

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 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.