A new sub strain of the Omicron Covid variant has a higher growth rate and could be more transmissible, the UK Health Security Agency (UKHSA) has said.
Known as the BA.2 Covid strain, the variant is said to spread faster than the original and is thought to have been identified more than 420 times in the UK since November, with cases multiplying in some parts of Europe and India.
Also known as the 'Stealth Variant', it is now known to be circulating in more than half of all USA states, the Centers for Disease Control and Protection (CDC) announced yesterday.
UKHSA said that BA.2 had an increased growth rate compared to BA.1 in all regions of England where there were enough cases to assess it.
Dr Susan Hopkins, chief medical adviser for UKHSA, said: "We now know that BA.2 has an increased growth rate which can be seen in all regions in England.
"We have also learnt that BA.2 has a slightly higher secondary attack rate than BA.1 in households.
"Although hospitalisations and deaths remain low, cases are still high in some areas and some age groups so it’s important that we continue to act cautiously as restrictions are lifted.
"Consider wearing a face covering when in crowded places. Take a vaccine to protect yourself against Covid-19. If you have any symptoms, take a test."
Experts said while the new version appears to spread more easily, early results suggest vaccines are just as effective against it.
Worldwide data suggests that Denmark is currently the epicentre of the new variant, with more than 6,400 confirmed cases.
But medics have said they do not believe there is cause for alarm, with new mutations always expected.
Anders Fomsgaard, chief physician and virus researcher at the Statens Serum Institut (SSI), told Danish media: "We cannot see any difference in hospitalization numbers, death rates with BA.2, so it is not something that worries us yet.”
He said that BA.2 is still "a new piece in the Covid game", but continued: “Right now we should just treat it as yet another variant until new data should eventually show other results."
Virologist Dr Tom Peacock, from Imperial College London, said he is confident that the new sub-variant is not a mixture of Delta and Omicron.
He told the Daily Mail : "Even with slightly higher transmissibility this absolutely is not a Delta to Omicron change, and instead is likely to be slower and more subtle."
