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What are the new ‘Stratus’ Covid symptoms as cases rise across UK

New XFG.3 variant accounts for a larger proportion of infections than any other

Holly Evans
Monday 06 October 2025 06:27 BST
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New Covid strain arrives in the UK
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A new strain of Covid, with a unique symptom, is circulating in the UK, accounting for a high proportion of cases in England.

The new strain, called Stratus, has two variants, XFG and XFG.3, with some experts suggesting that the variant is known for its unique symptom of giving people a hoarse voice.

Despite accounting for a large proportion of new cases, experts are not concerned about the spread, noting it is normal for viruses to mutate and change.

“It is normal for viruses to mutate and change over time,” Dr Alex Allen, consultant epidemiologist of the UK Health Security Agency (UKHSA), said, adding that it continues to monitor all strains of Covid in the UK.

This new variant is known for its unique symptom of giving people a hoarse voice
This new variant is known for its unique symptom of giving people a hoarse voice (Alamy/PA)

By 10 September, the UKHSA noted a 7.6 per cent increase in coronavirus cases across England compared to the previous week, although it’s uncertain how many are linked to the XFG variant.

What is ‘Stratus’ XFG and XFG.3?

The World Health Organisation has designated the XFG as a “variant under monitoring” and has said the additional public health risk posed by XFG is evaluated as low at the global level.

Globally, XFG was estimated to have the highest relative growth compared to other variants currently circulated, including the recent “Nimbus” NB.1.8.1.

Due to fewer people testing for Covid, it is increasingly difficult for experts to track infections
Due to fewer people testing for Covid, it is increasingly difficult for experts to track infections (Getty/iStock)

Current data does not indicate that this variant leads to more severe illness or deaths than other variants in circulation, the organisation said.

What are the symptoms of Stratus Covid strain?

While evidence shows an increased proportion of XFG, the WHO has not observed any signs that it has an increase in severity.

Dr Allen from the UKHSA also noted: “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.”

It comes as new Covid variants continue to spread throughout the country, with Nimbus giving people razor-blade-like sore throats last month.

Some experts have claimed that Stratus can give patients a “hoarse voice”.

XFG has been detected in Europe, southeast Asia and the Americas
XFG has been detected in Europe, southeast Asia and the Americas (Getty/iStock)

What are the risks around XFG?

The WHO have designated XFG as a “low risk” globally.

It said: “XFG is growing rapidly compared to co-circulating variants globally. However, XFG exhibits only marginal additional immune evasion over [other variant] LP.8.1. While there are reported increases in cases and hospitalisations in some of the [southeast Asia region] countries, which has the highest proportion of XFG, there are no reports to suggest that the associated disease severity is higher as compared to other circulating variants.

“The available evidence on XFG does not suggest additional public health risks relative to the other currently circulating Omicron descendant lineages.”

Do the Covid vaccines work against new strains?

Based on available evidence, the WHO said the current approved Covid vaccines are expected to remain effective against this variant against symptomatic and severe disease.

The organisation said the current data suggests the risk of vaccine evasion is low, however, additional laboratory studies are needed to further assess the risk of antibody escape.

However, some experts have warned that Stratus could also evade immunity from jabs.

“Unlike other variants, Stratus has certain mutations in the spike protein which could help it evade antibodies developed from prior infections or vaccinations,” Dr Kaywaan Khan, Harley Street GP and founder of Hannah London Clinic, told Cosmopolitan UK.

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