Key points
- A new Covid strain known as Stratus is spreading across the UK
- The variant is marked by a distinctive symptom: a hoarse or raspy voice
- Sub-variants XFG and XFG.3 now account for 30% of cases in England
- Experts say there is no evidence of more severe disease
- Lower immunity levels may make more people vulnerable to infection
Covid variant Stratus on the rise in the UK
A new strain of Covid-19, known as Stratus, is spreading across the UK and drawing attention for its unusual symptom — a hoarse or raspy voice. According to data from the UK Health Security Agency (UKHSA), Stratus and its two sub-variants, XFG and XFG.3, are responsible for around 30 per cent of Covid cases in England.
Of the two, XFG.3 is currently the more dominant. The UKHSA confirmed that monitoring of all circulating Covid-19 variants is ongoing as part of regular surveillance.
Mutations help Stratus spread despite immunity
Experts have raised concerns about the immune-evasive nature of the Stratus strain. Dr Kaywaan Khan, a Harley Street GP and founder of Hannah London Clinic, noted that certain mutations in the spike protein could help the virus bypass antibodies generated by previous infection or vaccination.
“Unlike other variants, Stratus has certain mutations in the spike protein which could help it evade antibodies developed from prior infections or vaccinations,” said Dr Khan. However, the symptoms tend to remain mild to moderate, with hoarseness being one of the most noticeable.
Dr Alex Allen, Consultant Epidemiologist at the UKHSA, said, “It is normal for viruses to mutate and change over time,” adding that there is currently no evidence that the XFG or XFG.3 variants cause more severe disease than previous strains.
Waning immunity raises infection risk
According to Professor Lawrence Young, a virologist at the University of Warwick, the reduction in Covid-19 infections in recent months, along with lower booster jab uptake, could increase the risk of infection.
“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,” he told MailOnline.
He warned that this could lead to a new wave of infections, though the scale remains uncertain.
Global monitoring of the strain
Globally, Stratus accounted for 22.7 per cent of Covid cases as of 22 June, according to the World Health Organisation (WHO). The strain has been designated as a “variant under monitoring”, with WHO currently assessing its public health impact as low risk.
The emergence of Stratus follows the spread of another recent variant called Nimbus (NB.1.8.1), first detected in China and Hong Kong in January and now present in parts of the US and Australia. Nimbus has been associated with more severe sore throat symptoms.
Reduced testing levels since the pandemic’s peak make it difficult to track the true spread of these new variants, health officials have noted.
