The XFG Covid variant, also known as Stratus, has become the dominant strain in the UK, accounting for more than half of positive Covid tests, according to latest figures. Cases of the virus have risen sharply, with hospital admissions also increasing significantly.
Data from the UK Health Security Agency (UKHSA) shows 1,374 Covid cases were recorded in August before the figure jumped by 230 per cent 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 per cent. The rate of positive Covid tests in hospitals also increased from 5.9 per cent to seven per cent in September.
What is the XFG Covid variant?
XFG, also known as Stratus, is currently the most common Covid variant in North America, which has led to it being dubbed "American Covid." It has also become dominant in the UK, accounting for more than half of positive tests. Additionally, cases have risen sharply over shorter periods. In the seven days to September 23, infections increased by almost 30 per cent, climbing from 1,061 to 1,374.
Like other viruses, Covid changes over time as it spreads. These changes are known as mutations, and when a virus changes enough, scientists refer to it as a variant. Dr Alex Allen, a consultant epidemiologist at the UKHSA, said: "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."
XFG is a spinoff of the Omicron variant, which emerged in 2021 and quickly became a major strain of Covid. The World Health Organisation identified XFG as a combination of earlier variants LF.7 and LP.8.1.2. The name XFG refers to the virus's genetic sequence, while Stratus was chosen as its public name. The strain was first designated in 2025 and has been circulating in Europe and North America since the end of that year.
What are the symptoms of XFG?
While XFG itself is not a brand-new strain, it has become increasingly common in the UK and is behind the recent rise in Covid cases. Dr Allen said: "While Covid-19 activity has shown some recent increases, cases remain at low levels in the UK." The doctor added: "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. 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."
The symptoms of XFG are similar to those seen with previous Covid variants. A sore throat appears to be one of the more common symptoms, but people can experience a range of symptoms. These can include fever, fatigue, cough, sneezing, a runny or blocked nose, and nausea, vomiting or diarrhoea.
The NHS has stated that most people who develop symptoms do not need to take a lateral flow test. However, anyone who thinks they have Covid is advised to avoid contact with other people for five days. While for those under 18, the advice is to stay away from other people for three days. Anyone who tests positive should also avoid meeting people with weakened immune systems for 10 days from the day they took the test.
