‘Kraken’ Covid variant XBB.1.1 could become dominant in UK as experts warn vaccines ‘best defence’

A new Covid variant dubbed “the kraken” could become the dominant strain in the UK, experts have warned.

The strain - officially named XBB.1.5 - is a “sub lineage” of the Omicron variant and has been branded the “most transmissible yet” by the World Health Organisation (WHO).

The variant is a mutated version of Omicron XBB, which was first detected in India in August last year, according to outbreak.info which uses data from the Global Initiative on Sharing Avian Influenza Data (GISAID).

Concern about the kraken is largely due to how rapidly it is spreading in the United States, causing cases of the variant to more than double in a week. The strain now accounts for more than 40% of Covid cases in America, according to recent data releases from the Centers for Disease Control and Prevention (CDC), and it has been detected in at least 29 countries - including the UK.

Dr Maria Van Kerkhove, WHO’s technical lead for Covid, told a press conference last week: “We are concerned about its growth advantage in particular in some countries in Europe and in the US... particularly the Northeast part of the United States, where XBB.1.5 has rapidly replaced other circulating variants.

“Our concern is how transmissible it is… and the more this virus circulates, the more opportunities it will have to change.”

She added: “We do expect further waves of infection around the world, but that doesn’t have to translate into further waves of death because our countermeasures continue to work.”

Health experts have stressed that XBB.1.5 is not more dangerous than the original Omicron variant, but warned that 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. The Omicron sub lineage known as BQ.1 is currently the dominant UK strain.

‘Vaccination best form of defence’

Studies have found that the variant is capable of evading antibodies from previous Covid infection or vaccination, but it has not yet been listed as a variant of concern by the UK Health Security Agency (UKHSA).

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. Neither have been designated as variants of concern by UKHSA.”

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.”

The warning over the new variant comes as Covid infections in the UK have jumped to their highest level since the summer, with experts warning the current wave could be the biggest the country has seen.

Infections peaked at 4.3 million last winter during the spread of the Omicron variant of Covid, but this was topped a few months later during the wave caused by the Omicron BA.2/3 subvariants, when infections reached a record 4.9 million.

Recent data from the Office for National Statistics (ONS) shows almost three million people are estimated to have had the virus in the week to 28 December 2022 - more than double the number at the start of the month and the highest total since mid-July.

The surge in infections has not been linked to a specific new variant, but is instead thought to be due to an increased amount of social mixing and airborne transmission, particularly during the cold weather when more people are likely to be indoors.