A new COVID-19 variant nicknamed “Stratus” is rapidly spreading across the United Kingdom, adding another chapter to the ongoing pandemic story. The variant, known scientifically as XFG and its offshoot XFG.3, now accounts for approximately 30% of all COVID cases in England – a sharp rise from just 10% in May.
Health experts identify Stratus as a descendant of the Omicron lineage. What makes this variant notable is its nature as a “recombinant” or “Frankenstein” strain, meaning it emerged when someone was infected with two different COVID variants simultaneously, creating a hybrid version of the virus.
“It is normal for viruses to mutate and change over time,” explains Dr. Alex Allen, Consultant Epidemiologist at the UK Health Security Agency (UKHSA). The agency continues to monitor all COVID strains circulating in the UK and abroad.
The World Health Organization (WHO) has designated Stratus as a “variant under monitoring,” asking health authorities worldwide to track it closely. Despite this designation, WHO currently assesses the global public health risk as “low.”
Distinctive Symptoms
While Stratus shares many symptoms with previous COVID variants, doctors have noted some distinctive features. Dr. Kaywaan Khan, a Harley Street GP, points out that “one of the most noticeable symptoms of the Stratus variant is hoarseness, which includes a scratchy or raspy voice.”
Some patients have also reported what’s being described as a “razor blade” sore throat – an intensely painful sensation that sets this variant apart. Additionally, gastrointestinal issues such as nausea and diarrhea have been observed in some cases.
Other common symptoms remain similar to previous variants and include:
- High temperature
- New continuous cough
- Fatigue and body aches
- Blocked or runny nose
- Loss of appetite
Global Spread
The Stratus variant isn’t limited to the UK. WHO data shows it accounted for 22.7% of global COVID cases as of June 22, 2025. The variant has been detected in multiple countries, with notable presence in India where genome sequencing studies found it to be dominant in Maharashtra state.
Another variant called “Nimbus” (NB.1.8.1) is also circulating globally. This strain has been detected in at least 22 countries and has shown rapid growth in the United States, China, and other Asian nations including Hong Kong, Singapore, and Thailand.
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Immune Evasion Concerns
Some experts have raised concerns about Stratus’s ability to evade immunity gained from previous infections or vaccinations.
“Unlike other variants, Stratus has certain mutations in the spike protein which could help it evade antibodies developed from prior infections or vaccinations,” explains Dr. Khan. Research indicates there may be a roughly two-fold reduction in antibody effectiveness against XFG compared to other circulating variants.
Professor Lawrence Young, a virologist at Warwick University, notes: “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.”
Severity Assessment
The good news is that current evidence suggests Stratus does not cause more severe illness than previous variants. Dr. Allen confirms: “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.”
In India, Dr. Ameet Dravid has observed that while XFG is highly transmissible, its capacity to damage lungs or cause severe complications appears minimal, with most cases recovering with outpatient treatment.
Current Situation
As of late June, the UKHSA reports that “COVID-19 activity decreased across most indicators” and was at baseline levels. Hospital admissions in England dropped to 0.99 per 100,000 compared to 1.46 the week before, and the number of positive tests in GP surgeries fell to 7.8% from 8.8%.

Public health officials continue to recommend staying up-to-date with COVID vaccinations, maintaining good hygiene practices, and getting tested if symptoms appear. While testing is no longer free in many areas, tests remain available for purchase.
The emergence of new variants like Stratus serves as a reminder that the virus continues to evolve, requiring ongoing vigilance from both health authorities and the public.