World Health Organisation warns XBB.1.5 is the ‘most transmissible’ Covid variant yet

A new strain of Covid nicknamed ‘The Kraken’ is ‘the most transmissible subvariant that has been detected yet’, according to the World Health Organisation.

The latest subvariant – another spinoff of Omicron officially named XBB.1.5 – has already taken hold in the US where it is thought to be behind roughly 70 per cent of new infections in the worst affected areas and 4 in 10 overall.

Now it has started to sweep across the UK, indicating it has a major growth advantage over rival strains.

But XBB.1.5 appears to be just as mild as its ancestor Omicron and its variants. 

A new strain of Covid nicknamed ‘The Kraken’ is ‘the most transmissible subvariant that has been detected yet’, according to the World Health Organisation  

Dr. Maria Van Kerkhove, WHO’s technical lead for Covid, told a press conference Wednesday: ‘We are concerned about its growth advantage in particular in some countries in Europe and in the US’

Concern about XBB.1.5 is largely based on how it is currently surging in the US, but it has also already been spotted in Britain and other countries around the globe.

Dr. Maria Van Kerkhove, WHO’s technical lead for Covid, told a press conference Wednesday: ‘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.’ 

Statistics from the US Centres for Disease Control and Prevention (CDC) showed the strain is behind 41 per cent of cases in America.

In the UK meanwhile, data from GISAID and CoVariants.org suggests that XBB.1.5 was responsible for just under 8 per cent of cases in the two weeks to January 2. 

But the latest figures from the Sanger Institute, one of the UK’s largest Covid surveillance centres, suggests XBB.1.5 is behind up to half of all Covid cases in the worst-hit regions.

The Sanger Institute’s research shows 50 per cent of cases in Wirral last week were caused by the ‘Kraken’.

XBB.1.5 has also been detected in countries including France, Germany, the Netherlands, Spain, Ireland, Australia, Singapore and India.

Data from GISAID and CoVariants.org suggests that XBB.1.5 was responsible for just under 8 per cent of cases in the UK in the two weeks to January 2.

Scientists estimate XBB.1.5 is behind 50 per cent of Covid cases in the worst hit areas in Britain

Experts are concerned XBB.1.5’s rapid rise could be caused by mutations that help it to better infect people and dodge protection from vaccination and prior infections.

Professor Lawrence Young, a virologist at Warwick University, told MailOnline that the emergence of the strain is a ‘wakeup call’ and could exacerbate the NHS crisis in Britain.

He said: ‘The XBB.1.5 variant is highly infectious and is driving increased hospital admissions in New York, particularly among the elderly. 

‘Waning immunity, more indoor mixing because of the cold weather and lack of other mitigations, such as wearing facemasks, are also contributing to this surge of infection in the US.’

XBB.1.5 has gained 14 new mutations to the virus’ spike proteins compared with its ancestor strains, which appear to have given it enhanced antibody-resistance.

This means people who are vaccinated or have had a previous infection are more susceptible to an infection – though not necessarily severe illness.

But what appears to be spooking the WHO is the prospect of XBB.1.5 being the gateway to a scarier variant.

The more infections that occur, the more opportunities the virus has to mutate and evolve. 

The F486P vaccines could make it more resistant to antibodies brought on by the Covid vaccine. 

Some lab tests have indicated it can better evade jab-induced immunity, although the jury is still out in the real world. 

Professor Young said: ‘We don’t know how this variant is going to behave in the UK, in a population that has been previously exposed to other Omicron variants and where many of the over 50s have had booster shots with a bivalent vaccine.  

‘Nevertheless, this is a wakeup call — a sharp reminder that we can’t be complacent about Covid. 

‘The threat of XBB.1.5 and other Covid variants further exacerbating the current NHS crisis stresses the need for us to remain vigilant. 

‘We need to continue to monitor levels of infection with different variants in the UK, encourage those who are eligible to get their boosters shots — why not extend this to the under 50s? — and promote the value of other mitigation measures.’

Not all experts are so concerned, however. 

The Our World in Data graph shows the number of Covid cases logged daily, on average, in the UK (pink) and US (black) per million people. It shows the UK recorded 97 on December 27, while the US reported 183. However, the figures only reflect positive tests that are reported, so underestimate the true scale of infections 

Even if the vaccines do not work perfectly against the variant, immunity is likely to still hold up, with most Brits also having been exposed to former Omicron variants.

High levels of protection against the virus gave ministers the confidence to ditch all Covid measures last year as the country moved to living with the virus. 

Dr Simon Clarke, a microbiologist based at the University of Reading, told MailOnline that XBB.1.5’s ability to evade immunity has only been observed in the lab. 

‘So it’s difficult to know how this will translate into real life,’ he noted.

‘It doesn’t seem to be causing more serious disease than other circulating variants, which are the most important metrics to watch when tracking Covid,’ he said.

Dr Clarke added: ‘It will be interesting to see how the situation develops over the coming months as the usual annual wave of flu hospitalisations is usually highest in January and February.’

Professor Francois Balloux, an infectious disease expert based at University College London, told MailOnline: ‘It is far from clear XBB.1.5 will cause a massive wave on its own.’