What is XFG Covid strain? Symptoms to look out for as UK cases grow

Covid cases have more than doubled and hospital admissions are up five-fold this month, latest figures show.

The UK Health Security Agency (UKHSA) monthly figures show that in August, 1,374 contracted Covid. In September, this jumped 230 per cent to 4,589.

Thee figures show there were 950 hospital admissions for Covid in August and the total jumped to 4,939 in September, up by around 420 per cent.

UKHSA revealed the rate of positive Covid tests in hospitals increased from 5.9 per cent to 7 per cent, according to the latest figures in September.

More than half of the positive tests were found to be a variant of XFG, also known as the Stratus or “American Covid” strain, which was first identified last January and has since spread around the world.

How much have Covid cases increased by?

In one week alone, cases increased by almost 30 per cent. In the seven days to September 23, cases rose to 1,364 from 1,061 the previous week.

Hospitalisations also increased by 15 per cent to 261 in the week to August 31, according to UKHSA data.

However, the true number of infections may be higher, as UKHSA data comes from NHS England’s reports from tests on patients who become very unwell with the virus.

That means there could be far more people suffering from milder forms of Covid and have not been admitted to hospital or officially diagnosed.

But cases are still far below their peak in January 2021 when there were more than 20,000 people in hospital, according to UKHSA.

The recent spike comes as health officials urge eligible people to get their flu and Covid jabs ahead of the winter months when cases typically rise.

What is the XFG covid variant?

The XFG strain or “Stratus” has been in circulation in Europe and North America since the end of 2025.

The World Health Organisation identified it as a mix of earlier variants LF.7 and LP.8.1.2.

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.

“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.”

This winter’s vaccine is specifically designed to protect against this strain and its variants.

What are the symptoms?

Symptoms of the XFG strain are similar to previous variants. It can cause a sore throat, cough, fever and hoarseness.

But in most cases those who show symptoms do not need to take a lateral flow test, the NHS said.

However, the health service has advised those who think they have Covid to avoid contact with other people for five days, or three days for those under 18.

Everyone who tests positive should avoid meeting people with weakened immune systems for 10 days after the day they took the test.