Monday, 25 May 2026
XFG has been detected in Europe, South east Asia and the Americas (Getty/iStock)
What is the new ‘Stratus’ Covid variant?
A recently identified Covid strain with a distinct symptom is spreading across the UK and now accounts for a significant share of current cases in England, according to the Independent.
Named Stratus, this strain includes two variants—XFG and XFG.3—with XFG.3 representing 30 percent of new infections nationwide.
Unusually, the Stratus variant has been linked to a hoarse voice, a symptom that distinguishes it from previous Covid strains, some experts say.
Despite its growing prevalence, health officials remain unconcerned. Experts emphasize that viral mutations are a normal part of how viruses evolve and adapt.
“It is normal for viruses to mutate and change over time,” confirmed Dr. Alex Allen, consultant epidemiologist at the UK Health Security Agency (UKHSA), noting that all Covid variants are under ongoing surveillance.
The World Health Organization (WHO) has classified XFG as a “variant under monitoring,” assessing its additional global public health risk as low.
Globally, XFG is displaying the fastest growth rate among currently circulating variants, including the recent “Nimbus” (NB.1.8.1) strain.
According to the WHO, there’s no current evidence that XFG results in more severe illness or increased mortality compared to other existing variants.
While data shows a rising proportion of XFG cases, WHO has not observed any signs that this variant leads to greater disease severity.
“In some countries within the [South-east Asia Region], where XFG is most common, case numbers and hospitalisations have increased,” WHO reported, “but there’s no indication the severity is greater than with other circulating variants.”
Dr. Allen added, “Based on available information, there’s no evidence that XFG or XFG.3 causes more severe disease than earlier variants, and no indication that current vaccines are less effective against them.”
The emergence of Stratus comes as various new Covid strains continue to appear across the country. Just last month, the Nimbus variant was noted for its distinctive symptom of causing razor-blade like sore throats. Now, experts indicate Stratus may give patients a “hoarse voice.”
What are the risks associated with XFG?
WHO has officially classified XFG as presenting a “low risk” on a global scale.
They stated, “XFG is expanding quickly compared to other circulating variants around the world. However, it only shows minimal additional immune evasion over the LP.8.1 variant. While case and hospitalisation numbers have increased in some [South-east Asia Region] countries, where XFG is most prevalent, there are no reports suggesting a rise in disease severity versus other current variants.
“The current evidence on XFG does not indicate increased public health risks compared to other Omicron descendant lineages that are circulating now.”
Are existing Covid vaccines effective against NB.1.8.1?
Based on current findings, WHO says regulatory-approved Covid-19 vaccines are still expected to protect against both symptomatic and severe disease from this variant.
The agency added that early evidence points to a low risk of vaccine escape, though further research is required to clarify the potential for antibody evasion.
Yet some experts caution that Stratus might also evade immunity from vaccinations.
“Stratus differs from previous variants, as it has mutations in the spike protein that could allow it to sidestep antibodies formed from earlier infections or vaccinations,” Dr. Kaywaan Khan, Harley Street GP and founder of Hannah London Clinic, told Cosmopolitan UK.