A new variant of Covid-19, arthritis, accounts for a quarter of all cases in the UK, data shows.
According to the UK Health Security Agency (UKHSA), a substrain of the Omicron variant known as CH.1.1 is one of the possibilities to replace the currently dominant BQ.1.
Since the first cases of the new variant appeared in November, it had spread to 23.1% of all cases in the UK by January 1, the latest figures from the UKHSA show – although sequencing suggests it could be as high as 100% in some areas.
Figures from that week suggest arthritis is responsible for about 8,700 cases, although officials caution that different estimates are uncertain.
The Arthrus variant, along with Kraken or XBB.1.5, is believed to be on track to become dominant in Great Britain – although not classified as “of concern”.
The XBB.1.5 variant has been on the rise in the US in recent months, becoming dominant two weeks ago, but remains very limited in UK prevalence.
Genomic mapping by the Sanger Institute, a research group partly funded by the government, shows that arthritis has taken over parts of the UK.
Uncertainty in Sanger’s modeling is high, but the data show that 100% of recent cases in regions across the country can be attributed to arthritis.
These include Northumberland, Bradford, Wakefield, Blackburn with Darwen, North West Leicestershire, Breckland, Central Bedfordshire, Oxford, Reading, Woking, Enfield, Havering, Sevenoaks, Crawley and Atour.
Blackburn with Darwen has the highest percentage of cases when taking the difference between the lowest estimate of 43 per cent and the highest estimate of 100 per cent.
The first UK area to register arthritis for Sanger’s modeling was Blaby in south-west Leicestershire in the week before 12 November.
The new variant, like Omicron and Kraken before it, takes its name from Greek mythology. In ancient mythology, Arthrus was a two-headed dog who guarded a giant fortress.
Meera Chand, UKHSA’s director of clinical and emerging infections, said: “Through our genetic monitoring, we continue to see the evolution of variants in the Omicron family.
“UKHSA continues to monitor the situation and is working to understand the public health implications.
“Vaccination is our best defense against future waves of Covid-19, so it’s even more important that people get all the doses they deserve as soon as possible.”
Officials have welcomed the drop in Covid-19 cases, which spiked in December, adding to pressures on the NHS.
The UKHSA’s latest data showed 28,009 cases in the week to January 7, down 25.8% from 37,757 in the previous week, as the number of people hospitalized in England with Covid-19 fell to pre-Christmas levels.
Health experts said the figure was “encouraging and welcome”, but stressed the importance of getting the last booster shot, with a third of people over 50 still not getting the vaccine.