Scientists tell The i Paper they expect the new Nimbus variant to fuel a new wave in the UK this summer
Scientists fear the UK will see a new Covid wave this summer as the new “Nimbus” variant spreads rapidly around the world.
The NB.1.8.1 variant – which has been dubbed Nimbus – is thought to be more contagious than the other active Covid variants, although there is no evidence that the symptoms are any more severe.
At the same time, the immunity Britons have built up from jabs and previous infections has waned considerably after relatively few cases of Covid over the last six months and a prolonged period of low vaccination levels.
As such, scientists are concerned the Nimbus variant could push up cases in the UK after sending infections soaring in China, Singapore and Hong Kong.
There are already signs that the Nimbus is spreading fast in the UK after its share of new Covid infections (from all variants) jumped from 2 per cent on 28 April to 11 per cent on 12 May, the latest date for which data is available, according to the COVspectrum database.
And while new infections are still well below the peaks seen last summer and autumn, there are signs that cases are starting to pick up in the UK.
New figures from the UK Health Security Agency (UKHSA) today indicate that new Covid infections rose by about 7 per cent in the week to Sunday 1 June – and are around 80 per cent higher than at the start of March.
It is not clear when any new wave would occur or how big it would be, but scientists say they do expect to see a spike in infections over the next month or two.
“We are very likely to see a spike of infections over the next couple of months, possibly by later this month or in July. But it’s difficult to predict the level of this infection wave,” Professor Lawrence Young, a virologist at Warwick University, told The i Paper.
“Population immunity, either from vaccination or previous infection, is waning and, unlike other respiratory viruses such as flu, the Covid virus continues to spread in hot and humid weather.”
“The NB.1.8.1 variant has driven surges of infection in Asia over the spring and is now the dominant strain in Hong Kong and China. It is also spreading in the US and Australia,” Professor Young said.
“Preliminary evidence from lab studies suggests that NB.1.8.1 can infect cells more efficiently than previous variants and that it can partially evade the immune protection provided by antibodies from vaccinated or previously infected people”.
The Nimbus variant – what we know
NB.1.8.1 now accounts for 10.7 per cent of global infections, according to the World Health Organisation (WHO). It has quickly become dominant in China, and is taking over in Singapore, Hong Kong, Taiwan and Australia. And in the UK it more than quadrupled in a fortnight to stand at 11 per cent of Covid infections – since when it is assumed to have grown further.
There is no evidence that Nimbus causes more severe symptoms, but experts believe it is more contagious because it can infect cells more efficiently. It can trigger gastrointestinal symptoms such as diarrhoea, constipation and nausea.
The variant was first recognised in January 2025 and the WHO has now designated it as a “variant under monitoring”. This means the WHO is closely tracking the virus for signs that it could pose a significant threat to the public in the future but it has not yet elevated it to “variant of concern” status.
Professor Young urged those who are eligible to take up their booster vaccines as the World Health Organisation has said that jabs still offer good protection against severe disease from infections by the Nimbus variant.
Free vaccines are still available for people aged 75 years and older, residents in care homes for older people, and those aged six months and over with a weakened immune system until 17 June in the current spring booster campaign.
Professor Christina Pagel, a healthcare data analyst at University College London, added: “It’s quite possible we will see a large wave of infection here in two months or so once it becomes dominant.”
Professor Steve Griffin, of Leeds University, said: “The UK has been fortunate not to have a major wave of Covid infections since last autumn. But a recent surge in cases in South East Asian countries, signifies that the relatively quiet spell may be coming to an end.”
Professor Paul Hunter, of University of East Anglia, said: “I guess we will see some increase in reported infections. I doubt case numbers will be as high as this time last year though I cannot be 100 per cent certain on this. But we do need to follow its progress”.
The UKHSA said today that 5.9 per cent of those people with respiratory symptoms testing for Covid in hospitals tested positive in the week to Sunday.
That “positivity rate” compares to 16.2 per cent in last July’s peak and 2.3 per cent at the start of the year.
Positivity rates among hospital patients with symptoms are typically much higher than infection rates in the general population – figures which are not available for the UK outside of winter.
Although the figures are not available for the UK and only cover England, scientists say they give a good indication of trends and across the four nations.
Covid booster vaccine
You can get a Covid-19 vaccine if you:
- are aged 75 or over (including those who will be 75 by 17 June 2025)
- are aged 6 months to 74 years and have a weakened immune system because of a health condition or treatment
- live in a care home for older adults
The spring booster vaccine campaign runs to 17 June in England, and 30 June in Scotland, Wales and Northern Ireland.
To book an appointment, you can visit the NHS website or call 119. Those ineligible for an NHS booster can also purchase
