Nocturnal 
Covid is back in the headlines this autumn, and a variant called XFG, nicknamed “Stratus” or “American Covid”, is being blamed for a sharp rise in cases and hospital admissions across the UK.
Latest UK Health Security Agency (UKHSA) figures, published on 8 October, show the rate of positive Covid tests in hospitals rose from 7.9% to 9.1% in the week ending 4 October 2026, while weekly hospital admissions climbed from 1.75 to 2.04 per 100,000 people. A total of 1,638 Covid cases were identified in hospital settings that week, up from 1,328 the week before, with positivity highest among the over-85s, where rates jumped from 10.4% to 13.1%.
Separate UKHSA data cited by The Sun showed 1,857 Covid cases reported in England in the week to 30 September, a 34.6% rise on the previous week, alongside 1,168 hospital admissions, up 33.5%. Figures reported by the Mirror and the London Evening Standard also pointed to a steep climb through September, with national case numbers and hospitalisations both rising sharply compared with August, and London recording its highest Covid case levels in a year.
Although outlets have used slightly different weekly snapshots from UKHSA’s rolling surveillance, the overall picture is consistent: Covid activity is rising noticeably this autumn, and XFG now accounts for the majority of sequenced positive samples.
What is the XFG variant?
XFG was first identified in January 2025 and has since spread globally. The World Health Organisation classifies it as a mix of two earlier variants, LF.7 and LP.8.1.2, and it is itself a descendant of Omicron. The WHO designated XFG a “variant under monitoring” on 25 June 2025.
It has been nicknamed “American Covid” because of where it was first sequenced and detected, rather than where it actually originated, UKHSA consultant epidemiologist Dr Alex Allen told The Sun. “That’s been circulating in some form or another in the UK for over a year now, and it’s only in the last couple of months we’ve actually seen this increased activity,” she said.
Dr Allen also told BBC Radio London that “the strains currently going around, including those known as XFG, are closely related to strains that have been with us for over a year, so this isn’t something new.”
Why it matters
Experts say the rise is being driven by a mix of familiar seasonal factors: children returning to school, students mixing at university, and colder weather pushing people indoors into poorly ventilated spaces, rather than the variant itself being unusually dangerous.
UKHSA has stressed there is no evidence XFG causes more severe illness or deaths than other circulating variants. “As increases in hospitalisations are rising in line with overall increases in Covid-19 circulation — rather than rising sharply on their own — this suggests a general increase in Covid-19 activity rather than a variant causing more severe disease,” the agency said.
Still, the strain on the NHS is a concern heading into winter. Professor Frankie Swords, NHS National Medical Director, warned: “Staff are already seeing the ominous early signs of pressure, with more patients coming to A&E with flu and other respiratory viruses than usual for this time of year.” She urged people to take up flu, RSV and Covid vaccinations if eligible.
Symptoms to watch for
Symptoms linked to XFG are broadly similar to those seen in earlier Covid waves: a sore throat, cough, fever, blocked or runny nose, headache, high temperature and shivering. This winter’s Covid vaccine has reportedly been specifically designed to offer protection against XFG and its variants, and current vaccines are expected to remain effective against the strain.
The NHS advises anyone with a high temperature, or who doesn’t feel well enough to go to work or school, to stay at home and avoid contact with others. Those who test positive are advised to avoid contact with people for five days, or three days for under-18s, and to steer clear of anyone with a weakened immune system for 10 days after testing positive.
UKHSA says it will continue monitoring the situation through GP appointments, A&E attendances, hospital admissions and genomic sequencing as the variant continues to circulate through the colder months.
[{“name”: “Daily Express”, “url”: “https://www.express.co.uk/life-style/health/2255603/12-symptoms-american-covid-xfg”}, {“name”: “The Sun”, “url”: “https://www.thesun.co.uk/health/40609321/freshers-flu-covid-symptoms-variant-xfg-coronavirus/”}, {“name”: “The Mirror”, “url”: “https://www.mirror.co.uk/news/uk-news/xfg-american-covid-nhs-pandemic-37747862”}, {“name”: “London Evening Standard”, “url”: “https://www.standard.co.uk/news/london/covid-london-american-xfg-strain-cases-hospital-b1300002.html”}]
A UK hospital ward or A&E waiting area, or a generic image of someone being tested for Covid, reflecting the rise in cases this autumn.
