XFG Covid Strain Fuels Sharp Rise in UK Cases and Hospitalisations
Covid-19 cases and hospital admissions in the UK have surged sharply this month, driven by the XFG variant—also known as the Stratus or "American Covid" strain. According to the UK Health Security Agency (UKHSA), cases jumped 230 per cent from 1,374 in August to 4,589 in September, while hospital admissions rose by approximately 420 per cent, from 950 to 4,939 over the same period. The rate of positive Covid tests in hospitals increased from 5.9 per cent to 7 per cent in September, with more than half of positive tests attributed to XFG.
In the week to September 23 alone, cases rose nearly 30 per cent, reaching 1,364 from 1,061 the previous week. Hospitalisations were up 15 per cent to 261 in the week ending August 31. However, health officials note that the true number of infections is likely higher, as UKHSA data only reflects tests on patients who become severely unwell—meaning milder cases often go undiagnosed. Despite the recent spike, hospitalisations remain far below the January 2021 peak, when more than 20,000 people were hospitalised with Covid.
What Is the XFG Variant?
XFG, or “Stratus,” was first identified in January 2025 and has since spread globally. The World Health Organization classifies it as a recombinant of earlier variants LF.7 and LP.8.1.2. It has been circulating in Europe and North America since late 2025. This winter’s vaccine is specifically designed to protect against this strain, and health officials are urging eligible individuals to get both flu and Covid jabs ahead of the colder months.
Alex Allen, consultant epidemiologist at UKHSA, said: “While Covid-19 activity has shown some recent increases, cases remain at low levels in the UK. UKHSA is monitoring all the data relating to Covid-19 variants in the UK and abroad, and we continue to publish our findings in our regular surveillance reports.”
Rising Hospitalisations Put Pressure on Health System Ahead of Winter
The sharp rise in admissions—up more than five-fold in a month—comes as the NHS prepares for winter, a period when respiratory viruses typically circulate more widely. While the current wave is nowhere near the crisis levels seen earlier in the pandemic, the rapid increase in hospitalisations could strain resources if the trend continues. There is no evidence that XFG causes more severe disease than previous variants, but it can still lead to serious illness in those at greatest risk, including the elderly and immunocompromised.
The latest figures also recorded seven deaths involving Covid in England in the week ending August 28, compared with six the previous week. While fatalities remain low, the uptick in cases and hospitalisations underscores the importance of vaccination and vigilance.
This recent surge mirrors patterns seen in other countries where XFG has become dominant. In the UK, the variant now accounts for more than half of positive tests, signalling its increased transmissibility. Health experts emphasise that while cases are rising, the situation is being closely monitored and the public should follow official guidance.
Vaccination and Public Health Response
This winter’s vaccine has been updated to target the XFG strain, and UKHSA is urging all eligible people—including those over 65, pregnant women, and individuals with underlying health conditions—to get vaccinated. The flu vaccine is also being offered alongside the Covid booster to maximise protection. The recent spike has prompted calls for increased uptake, as vaccine fatigue and reduced testing may be contributing to underreporting.
“The recent spike comes as health officials urge eligible people to get their flu and Covid jabs ahead of the winter months when cases typically rise,” the UKHSA noted in its report. The agency continues to publish regular surveillance data to track variant prevalence and disease severity.
Broader Implications: Living with Covid in a Post-Pandemic Era
The XFG-driven increase serves as a reminder that Covid-19 remains a circulating virus with the potential to cause periodic surges. While the world has largely moved on from pandemic-era restrictions, the virus continues to evolve, producing new variants that can evade immunity. The rapid rise of XFG highlights the need for ongoing genomic surveillance and flexible public health strategies.
Unlike earlier variants, XFG has not been linked to a significant increase in severe outcomes, but its high transmissibility means more people may become infected, indirectly leading to more hospitalisations. This pattern—higher cases without a proportional rise in severity—is typical as populations build immunity through vaccination and prior infection. However, vulnerable groups remain at risk, and health systems must be prepared to handle seasonal peaks.
The situation also underscores the importance of global cooperation in tracking and responding to emerging variants. The WHO’s identification of XFG as a recombinant variant illustrates how viral evolution can produce new challenges. As the northern hemisphere enters winter, countries are advised to bolster vaccination campaigns and maintain testing capacities.
For now, UK health officials remain cautiously optimistic. “Cases remain at low levels in the UK,” Allen reiterated, but the agency is not complacent. The coming weeks will be crucial in determining whether the surge continues or plateaus. The public is encouraged to stay informed, get vaccinated, and practice good hygiene to reduce transmission.
As the UK navigates another Covid-19 wave, the focus is on protecting the most vulnerable while keeping society open. The experience with XFG will add to the growing body of knowledge on how to manage Covid-19 as an endemic disease.
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