The XFG Covid variant, dubbed "American Covid", is spreading across the UK as cases of the virus rise sharply. The strain, also known as Stratus, now accounts for more than half of positive Covid tests in the UK, according to the latest figures.
Cases and hospital admissions climb
Data from the UK Health Security Agency (UKHSA) shows 1,374 Covid cases were recorded in August before the figure jumped by 230% to 4,589 in September. Hospital admissions involving Covid also increased from 950 in August to 4,939 the following month, a rise of around 420%.
The rate of positive Covid tests in hospitals also increased from 5.9% to 7% in September. In the seven days to September 23, infections increased by almost 30%, climbing from 1,061 to 1,364.
Variant origins and monitoring
XFG, also known as Stratus, is the most common Covid variant in North America, which has led to it being dubbed "American Covid". The strain has also become dominant in the UK, accounting for more than half of positive tests. It has been circulating in Europe and North America since the end of 2025, and the World Health Organisation identified it as a mix of earlier variants LF.7 and LP.8.1.2. The strain is an offshoot of Omicron, which emerged in 2021.
The true number of infections could be higher because UKHSA data is based on NHS England reports from tests involving patients who become very unwell with the virus. People suffering from milder forms of Covid who have not been admitted to hospital or officially diagnosed may not be reflected in the figures.
Official response and symptoms
Alex Allen, consultant epidemiologist at the UKHSA, said: "While Covid-19 activity has shown some recent increases, cases remain at low levels in the UK. We're also not seeing any evidence that these are making people more ill or spreading faster than before, and this year's autumn vaccine has been specifically designed to protect against them." He added: "UKHSA is monitoring all the data relating to COVID-19 variants in the UK and abroad, and we continue to publish our findings in our regular surveillance reports."
UKHSA says some people have reported a hoarse voice or a particularly painful sore throat associated with the latest variants. The painful symptom has been referred to in the media as "razor-blade throat". Despite the recent increase, cases remain far below the levels seen at the height of the pandemic, when more than 20,000 people were in hospital with Covid in January 2021.
Health advice and symptoms list
While Covid is not as severe for most people as it was during the early years of the pandemic, UKHSA says the virus continues to cause severe illness, hospitalisations and deaths, particularly among people with weakened immune systems and those aged 75 and over. Health officials are urging eligible people to get their Covid and flu vaccines ahead of the winter months, when respiratory viruses can circulate at high levels.
The NHS advises people who think they have Covid to avoid contact with others for five days, or three days for those under 18. Anyone who tests positive should avoid meeting people with weakened immune systems for 10 days after the day they took the test.
According to UKHSA's official guidance, symptoms people may experience include fever or chills, continuous cough, shortness of breath, tiredness, body aches, headache, sore throat, blocked nose, loss of appetite, nausea, diarrhoea, change in sense of taste or smell, hoarse voice, and a particularly painful sore throat.
