A new strain of Covid is spreading across the UK with some scientists warning it is resisting immunity. The Stratus strain, which already has two variants, is currently accounting for 30% of Covid cases across the UK.

“It is normal for viruses to mutate and change over time,” Dr Alex Allen, Consultant Epidemiologist of the UK Health Security Agency, said, adding that it continues to keep tabs on all strains of Covid in the UK. But what are the features of the new mutation, and what symptoms does it cause?

Stratus has two variants, XFG and XFG.3, according to UKHSA. XFG.3 accounts for more cases than any other individual variant.

However, Dr Allen explained that the new variants don’t appear to be any more threatening than previous ones. He said: “Based on the available information so far, there is no evidence to suggest that the XFG and XFG.3 variants cause more severe disease than previous variants, or that the vaccines in current use will be less effective against them.”

“One of the most noticeable symptoms of the Stratus variant is hoarseness, which includes a scratchy or raspy voice,” Dr Kaywaan Khan, Harley Street GP and Founder of Hannah London Clinic told Cosmopolitan UK.

Professor Lawrence Young, a virologist at Warwick University, toldMailOnline: “Given that immunity to Covid is waning in the population due to a decline in uptake of the spring booster jab and the reduction of Covid infections in recent months, more people will be susceptible to infection with XFG and XFG.3.

“This could lead to a new wave of infection but it’s difficult to predict the extent of this wave.”