UK officials have warned a Covid-19 variant dubbed “the kraken” could become one of the dominant strains in the UK, following its emergence and rapid growth in the US.
Against fears that the sub-variant is getting through vaccine-induced immunity, here’s what we know.
What is ‘the kraken’?
Earlier this month, the World Health Organisation (WHO) said XBB.1.5 is the most transmissible Omicron sub-variant that has been detected so far. It was quickly dubbed “the kraken” – a mythical sea monster of Scandinavian folklore – not by the WHO, but an informal group of scientists on social media anxious to bring attention to new strains.
Omicron is the most contagious variant of the virus causing Covid-19 that is now globally dominant. The new “sub-lineage” is an offshoot of XBB, first detected in October, which is itself a recombinant of two other Omicron sub-variants.
XBB.1.5 has a mutation known as F486P, which helps it to bypass Covid-fighting antibodies that were generated in response to vaccination or previous infection. Another change – S486P – is thought to improve its ability to bind to cells.
Virologists generally say new strains are to be expected, and the emergence of the sub-variants do not mean there is a new crisis in the pandemic.
The WHO said that it saw no indication that Omicron’s severity had changed, but it continues to monitor the strain given the lack of data surrounding it. While it could lead to a surge in infections around the world, current vaccines and treatments continue to protect against severe symptoms, hospitalisation and death.
Where has it been found?
The strain has been making up an increasing proportion of cases in the US, currently accounting for over 40% of infections in the country, according to data from the US Centers for Disease Control and Prevention.
According to the WHO, “the kraken” has now been identified in at least 29 other countries.
What have UK officials said?
On Tuesday, the UK Health Security Agency (UKHSA) said “the kraken” and another variant from the “Omicron family”, known as CH.1.1, do have a “growth advantage” and could become the dominant variants in the UK, experts have said.
At present the dominant variant in the UK is another Omicron sub lineage known as BQ.1.
A new technical briefing from the UKHSA states that XBB.1.5 “remains at very low prevalence in the UK, so estimates of growth are highly uncertain”.
But it adds: “CH.1.1 and XBB.1.5 are currently the variants most likely to take over from BQ.1 as the next dominant variant in the UK, unless further novel variants arise.”
Crucially, it added neither have been designated as “variants of concern”.
Dr Meera Chand, director of clinical and emerging infections at the UKHSA said: “Through our genomic surveillance we continue to see evolution of variants in the Omicron family.
“UKHSA is constantly monitoring the situation and working to understand the implications for public health.
“Vaccination remains our best defence against future Covid-19 waves, so it is still as important as ever that people come forward and take up all the doses for which they are eligible as soon as possible.”
Experts are still learning about Covid-19. The information in this story is what was known or available at the time of publication, but guidance could change as scientists discover more about the virus. To keep up to date with health advice and cases in your area, visit gov.uk/coronavirus and nhs.uk.