Covid cases are rising in Britain as England enters autumn, with the latest UK Health Security Agency (UKHSA) figures showing a sharp increase in hospital admissions and positive tests.
The weekly Covid-19 hospital admission rate in England rose from 0.81 to 1.20 per 100,000 people, an increase of about 48%. In London, the increase was even steeper, with the regional admission rate rising by roughly 79% in the latest reporting period.
Hospital testing is also showing more Covid activity. The proportion of PCR tests conducted in positive hospital settings increased from 5.9% to 7.0% in the week ending September 20, according to UKHSA surveillance data.
The rise comes as the XFG variant and its sublineages circulate in England. More than half of the sequenced infections in the latest UKHSA reporting period were classified as XFG-related lineages, although sequencing numbers remain relatively small, and the agency cautions that the most recent estimates should be interpreted carefully.
Why are Covid cases rising in Britain?
The increase comes at a familiar point in the respiratory-virus calendar, as people spend more time indoors and schools and workplaces become busier after the summer.
UKHSA currently describes Covid activity as increasing but still at a low level. Its September 24 surveillance report recorded rising hospital positivity and increased Covid-like attendances at emergency departments.
The increase also comes alongside rising influenza activity.
Influenza positivity in hospital settings increased to 3.8% in the same reporting period, up from 3.4% the previous week. Among samples tested in general practice, 10.7% were positive for influenza, compared with 8.3% the week before.
That creates a familiar autumn problem for doctors: several respiratory viruses can circulate at the same time, producing overlapping symptoms and making it difficult for people to know which infection they have without testing.
London is seeing a particularly sharp increase
London recorded the highest Covid hospital admission rate among England’s regions in the latest UKHSA report.
The rate increased by about 79% compared with the previous week, although the absolute rate remains relatively low. UKHSA’s September 10 report had already shown London with the highest regional admission rate, demonstrating that the capital had been experiencing elevated Covid activity before the latest increase.
The percentage increase therefore needs context. A large week-to-week percentage change can occur when the underlying number of hospital admissions is relatively small.
What is the XFG Covid variant?
XFG is a SARS-CoV-2 recombinant lineage that combines genetic material from two earlier lineages, LF.7 and LP.8.1.2.
The World Health Organization first documented XFG in a sample collected on January 27, 2025, and designated it a Variant Under Monitoring (VUM) in June 2025.
The variant has subsequently spread internationally and remains under surveillance by the WHO.
Importantly, XFG is not a newly emerged virus. It has been circulating for more than a year, although particular XFG sublineages have become more prominent at different times and in different countries.
UKHSA’s latest sequencing data illustrates that evolution. Among sequenced English cases collected between August 17 and August 30, 2026:
- 46.2% were classified as XFG.23.1.3
- 12.8% were XFG.14.8
- 5.1% were the broader XFG lineage
- Other detected lineages included NB.1.8.1, JN.1, TA.1 and XFJ.
Because sequencing numbers are limited, these percentages should not be interpreted as a precise measure of the prevalence of XFG across every Covid infection in England.
Is XFG really “American Covid” or “Stratus”?
Those names have appeared in media coverage, but they are not the official WHO designation.
WHO refers to the lineage as XFG and classifies it as a Variant Under Monitoring. The nickname “Stratus” has been used in some media and public-health discussions, while “American Covid” is an informal media label.
Calling it “American Covid” can also be misleading.
XFG was first identified in January 2025 and has circulated internationally. Its current presence in Britain does not mean that the virus was recently imported from the United States.
The WHO’s assessment is more important than the nickname: as of its June 2025 evaluation, there was no evidence that XFG caused more severe disease or deaths than other circulating variants. Existing Covid vaccines were expected to continue protecting against symptomatic and severe disease.
What symptoms does XFG cause?
There is no established evidence that XFG produces a completely new set of symptoms.
People infected with XFG can experience symptoms commonly associated with Covid, including:
- Cough
- Fever
- Sore throat
- Runny or blocked nose
- Headache
- Fatigue
- Muscle aches
Gastrointestinal symptoms such as nausea or diarrhea have also been reported in people with Covid infections, but they are not unique to XFG.
That means symptoms alone cannot reliably distinguish XFG from other SARS-CoV-2 lineages—or from influenza and other respiratory infections.
For people with symptoms that could be caused by several viruses, testing remains the more reliable way to establish whether Covid is involved.
Is XFG causing more severe Covid?
There is currently no evidence that XFG itself causes more severe disease than other circulating SARS-CoV-2 variants.
The WHO’s initial risk evaluation concluded that the additional public-health risk posed by XFG was low at the global level. It also found no evidence at that time that XFG caused more severe illness or deaths.
That does not mean COVID is harmless.
Older adults and people with certain underlying conditions remain at greater risk of severe disease, hospitalisation and death. A variant can also cause a substantial number of hospitalizations simply because it is circulating widely, even if it is not intrinsically more dangerous.
This distinction is important when interpreting the latest British figures.
Covid hospital admissions are rising—but remain at low levels
The nearly 50% increase in the weekly hospital admission rate sounds dramatic, but UKHSA currently characterizes overall Covid activity as low.
The latest rate of 1.20 admissions per 100,000 people is substantially below the levels seen during the major waves of the pandemic.
UKHSA also cautions that its hospital surveillance data is provisional and can be revised retrospectively.
The latest figures should therefore be read as evidence of an upward trend rather than proof of a new nationwide health crisis.
The numbers can also move quickly
Respiratory viruses often show substantial week-to-week changes.
The UKHSA dashboard currently records rising Covid activity across several indicators. Its latest data shows reported Covid cases increasing by 28.6% over seven days, although the agency warns that the most recent four weeks are particularly affected by reporting delays and may underestimate activity.
That means the trend is worth watching, but individual weekly changes should not be overinterpreted.
Could Covid be mistaken for flu?
Yes.
Covid and influenza can produce many of the same symptoms, including fever, cough, fatigue, headaches and body aches.
The overlap becomes particularly relevant in autumn and winter, when several respiratory pathogens circulate simultaneously.
UKHSA’s latest surveillance report shows that influenza activity is also increasing. Hospital flu positivity rose from 3.4% to 3.8% in the latest reporting week, while Covid hospital positivity increased from 5.9% to 7.0%.
Other viruses, including respiratory syncytial virus and common cold viruses, can further complicate the picture.
Are Covid deaths increasing?
Deaths involving Covid remain relatively low compared with the pandemic years, although the latest UKHSA dashboard recorded seven deaths in England in the week ending August 28, compared with six the previous week.
A one-week increase of one death does not establish a meaningful change in the fatality risk of the virus.
It is also important to distinguish between deaths involving Covid and deaths directly caused by Covid. Surveillance definitions can include people who had Covid recorded on their death certificate even when the infection may not have been the sole cause of death.
For that reason, mortality trends are more useful when examined over several weeks or months rather than from a single week’s figure.
What does the latest rise mean for Britain?
The latest data points to an autumn increase in Covid activity, rather than a return to pandemic-era conditions.
Three trends stand out:
- Hospital admissions are increasing. England’s weekly admission rate rose from 0.81 to 1.20 per 100,000.
- Hospital test positivity is increasing. The proportion of positive PCR tests rose from 5.9% to 7%.
- XFG-related lineages are widespread among sequenced infections. More than 60% of sequenced cases in the latest reporting window were classified as XFG.23.1.3, XFG.14.8 or XFG.
At the same time, UKHSA continues to classify overall Covid activity as low, and the WHO has not identified XFG as causing more severe disease than other circulating variants.
The key issue for the coming months will therefore be whether the current increase continues as Britain moves deeper into the respiratory-virus season.
What should people do as Covid levels rise?
Public-health advice is considerably different from the emergency measures used during the pandemic.
People who develop respiratory symptoms should take reasonable precautions, particularly around older adults and people who are medically vulnerable.
Practical measures include:
- Stay home if feeling significantly unwell or feverish.
- Improve ventilation when spending time indoors with others.
- Consider wearing a well-fitting mask in crowded indoor settings if symptomatic or at higher risk.
- Follow current NHS vaccination advice if eligible.
- Seek medical advice if symptoms become severe or breathing difficulties develop.
For most people, the latest rise in Covid infections does not represent a return to 2020 or 2021.
Instead, the data shows SARS-CoV-2 continuing to behave as a circulating respiratory virus, with activity fluctuating as new lineages emerge and seasonal conditions change.
The XFG lineage is part of that continuing evolution. While its spread is worth monitoring, current evidence does not show that it is a more dangerous variant. The more immediate concern for Britain’s health system is the combined burden of Covid, influenza and other seasonal respiratory infections as winter approaches.
