By Renewed interest in COVID-19 in the UK this autumn has been linked to the XFG COVID variant, widely known by its informal nickname Stratus. The variant is a descendant of the Omicron family and has become the most common lineage in recent sequencing data, according to the UK Health Security Agency (UKHSA).
UKHSA surveillance for September 2026 shows COVID activity has risen, with test positivity reaching around 7% and hospital admissions increasing. However, both UKHSA and the World Health Organization (WHO) say available evidence does not suggest XFG causes more severe disease than other currently circulating variants. Understanding what XFG is, what symptoms it causes, and how to protect vulnerable people remains important as we move into winter.
What Is the XFG COVID Variant?
SARS-CoV-2, the virus that causes COVID-19, constantly changes. Each time it replicates it can pick up small mutations. Most changes have little impact, but occasionally a lineage gains a growth advantage and spreads more widely. These are tracked as variants.
XFG is a recombinant variant. That means it formed when two existing Omicron subvariants infected the same person and swapped genetic material. According to WHO, XFG originated from parental lineages LF.7 and LP.8.1.2. The earliest sample was collected on 27 January 2025.
Why is it called Stratus? Informal nicknames like Stratus are given by researchers and media to make discussion easier. Stratus is not an official WHO name and does not indicate where the variant originated. Media in some countries have also called it “American Covid”, but WHO does not use that term and it does not reflect origin.
WHO designated XFG as a Variant Under Monitoring (VUM) on 25 June 2025. A Variant Under Monitoring is a signal for increased surveillance: WHO has identified genetic changes that could affect transmissibility or immune evasion and wants to track its spread. It is different from a Variant of Interest or a Variant of Concern, which require stronger evidence of impact on transmissibility, severity or vaccine effectiveness. Being placed under monitoring does not automatically mean a variant is more dangerous.
XFG carries several mutations in its spike protein, including changes in regions that help the virus bind to human cells and evade antibodies. Its rapid growth compared with co-circulating lineages is why it was placed under monitoring.
What Are the Symptoms of the XFG COVID Variant?
Symptoms reported for the XFG COVID variant symptoms are broadly similar to other Omicron-related infections. The NHS lists COVID-19 symptoms that can include:
- Sore throat, often described as scratchy or very painful
- Hoarse or raspy voice
- Cough, often dry or persistent
- Fever or chills
- Fatigue and feeling generally unwell
- Headache
- Runny or blocked nose and sneezing
- Muscle aches and joint pains
- Loss of or change to smell or taste, less common now than earlier in the pandemic
- Nausea, reduced appetite or mild diarrhoea in some cases
Most people have a combination of these rather than a single distinctive symptom. Symptoms can start 2 to 5 days after exposure and vary by age, prior immunity and underlying health.
Is a Hoarse Voice a Distinctive Symptom of Stratus?
Some media reports and pharmacist commentaries have highlighted hoarseness as a key symptom of Stratus COVID symptoms. UKHSA consultant epidemiologist Dr Alex Allen has noted that symptoms of the XFG strain include sore throat, cough, fever and a hoarse voice.
That has led to questions about whether a raspy voice is unique to XFG. Current evidence does not establish hoarseness as a reliable marker that distinguishes XFG from other variants. Anecdotal reports are useful for raising awareness, but sore throat and hoarse voice have been reported with many previous variants, including earlier Omicron lineages.
Importantly, symptoms alone cannot tell you which variant you have. Only genomic sequencing of a sample can identify a lineage, and sequencing is carried out on a small proportion of positive tests for surveillance purposes. If you have COVID-like symptoms, the approach to care is the same regardless of variant.
Is XFG More Dangerous Than Previous COVID Variants?
According to WHO tracking of SARS-CoV-2 variants and UKHSA risk assessments, there is currently no evidence that XFG causes more severe illness, higher rates of hospitalisation or higher mortality than other circulating Omicron variants.
WHO assessed the additional public-health risk posed by XFG as low in its June 2025 evaluation, finding no evidence of increased severity. UKHSA has similarly said that while activity has increased, cases remain at relatively low levels compared with previous waves.
It is important to separate spread from severity. A variant can become dominant because it spreads more easily or evades prior immunity to a degree, without causing more severe disease on average. However, when more people are infected, even a less severe variant can lead to more hospital admissions in absolute numbers, particularly among vulnerable groups. COVID-19 can still cause serious illness, especially for older adults and people with weakened immune systems, even when a variant is not classified as more severe overall.
Why Are COVID Cases Rising in the UK?
Latest UKHSA national flu and COVID-19 surveillance reports for September 2026 show an autumn increase:
- Rolling seven-day COVID-19 positivity in hospital settings increased from 5.9% to 7.0% in the week ending 20 September 2026.
- COVID-19 hospital admission rate increased from 0.81 to 1.20 per 100,000 people in the same week, an increase of around 48%, often reported as approximately 50%.
- Monthly data also showed hospital admissions rising from 950 in August to 4,939 in September across England, with London recording a 79% increase in admissions in one week, though weekly rates fluctuate.
- XFG, including its sublineage XFG.3, remained the most common circulating variant, accounting for more than half of sequenced positive samples in England in recent weeks.
UKHSA cautions that sequencing numbers are relatively low, so proportions should be interpreted carefully. A rise in hospital admissions does not prove a variant is more dangerous. Contributing factors typically include increased indoor mixing as schools return and temperatures drop, gradual waning of immunity from previous infections and vaccinations, and the natural wave-like pattern of respiratory viruses.
Increases have been observed consistently across England, Scotland, Wales and Northern Ireland, as well as in other parts of Europe and the United States, which points to seasonal behaviour rather than a UK-specific change.
How Does XFG Compare With Other COVID Variants?
In autumn 2026, several Omicron-derived lineages are co-circulating. Two others frequently mentioned by UKHSA are NB.1.8.1, nicknamed Nimbus, and BA.3.2, sometimes called Cicada in non-official discussion.
| Variant name | Lineage / classification | WHO monitoring status | Current evidence on severity | Limitations |
|---|---|---|---|---|
| XFG (Stratus) | Recombinant of LF.7 and LP.8.1.2, Omicron family | Variant Under Monitoring since 25 June 2025 | No evidence of increased severity vs other circulating variants; additional public health risk assessed as low | Severity data based on early observational studies; sequencing coverage limited |
| NB.1.8.1 (Nimbus) | Omicron sublineage | Variant Under Monitoring | No evidence of increased severity; widely co-circulating with XFG in UK | Immune evasion profile being monitored; evidence evolving |
| BA.3.2 (Cicada nickname, not official) | Highly divergent Omicron lineage with many spike mutations | Variant Under Monitoring | Some lab studies suggest stronger immune evasion, including reduced neutralisation in some groups; no confirmed increase in severity | Newer lineage; limited clinical severity data; mostly lab-based evidence |
JN.1 remains separately classified as a Variant of Interest, while XFG, NB.1.8.1 and BA.3.2 are listed as Variants Under Monitoring. WHO continues to publish regular risk evaluations as new data emerge.
Can You Get XFG After Having COVID Before?
Yes, reinfection remains possible. Immunity after infection or vaccination reduces risk but does not provide complete or permanent protection against infection, especially as the virus evolves.
Protection works on two levels:
- Protection against infection: Antibodies that help block infection can decline over months and may be less effective against variants with changed spike proteins. That is why people who had COVID in 2024 or 2025 can still catch XFG.
- Protection against severe disease: This tends to last longer, supported by memory cells that help limit how ill you become. Most people with prior immunity are less likely to develop severe illness than those with no immunity.
Previous infection still provides some protection, but it should not be assumed to prevent future infection entirely. This is similar to other respiratory viruses that circulate seasonally.
Do COVID Vaccines Still Protect Against XFG?
According to UKHSA and WHO, COVID-19 vaccines remain the best defence against severe disease and hospitalisation. Vaccines are expected to continue to provide protection against severe outcomes from XFG, although how well they prevent mild infection can vary depending on vaccine formulation, time since vaccination and individual factors.
The UK autumn 2026 programme is being offered from 1 October 2026 to 31 January 2027. NHS eligibility for the autumn COVID vaccine includes:
- Adults aged 75 years and over, including those who will turn 75 by 31 January 2027
- Residents in care homes for older adults
- People aged 6 months to 74 years who are immunosuppressed due to a health condition or treatment
The NHS contacts eligible people directly, but eligible individuals can also book via the NHS website without waiting for an invitation. UKHSA surveillance of last autumn’s programme showed those who were vaccinated were around 45% less likely to be admitted to hospital with COVID-19 from two weeks after vaccination compared with those who remained unvaccinated, with protection lasting around four months.
UKHSA has said the autumn vaccine formulation has been updated to target circulating variants. No vaccine provides complete protection, and effectiveness figures change over time, so official guidance should be followed.
What Should You Do If You Have XFG COVID Symptoms?
Current NHS guidance for respiratory infections applies regardless of variant. A routine lateral flow test generally cannot tell you which variant you have.
- Stay home if you have a high temperature or do not feel well enough to carry out normal activities.
- Avoid close contact with vulnerable people, including those who are immunosuppressed or elderly, while you have symptoms.
- If you test positive, try to avoid contact with others for 5 days after the positive result, or 3 days for those under 18, and avoid contact with immunocompromised people for 10 days.
- Practise good hand hygiene, cover coughs and sneezes, and dispose of tissues.
- Improve ventilation by opening windows when possible.
- Consider wearing a well-fitting face covering in crowded or poorly ventilated spaces if you have symptoms or are at higher risk.
- Follow current NHS advice on testing. Most people with mild symptoms do not need a lateral flow test unless advised by a healthcare professional.
If you are at increased risk of severe COVID-19, for example because you are immunosuppressed, contact your GP, NHS 111 or your specialist team promptly if you develop symptoms. You may be eligible for additional assessment or treatment.
Seek urgent medical attention if you experience severe breathing difficulty, persistent chest pain, confusion, or symptoms that worsen rapidly, in line with NHS advice. For children, seek help if they have persistent high fever, difficulty breathing, are unusually drowsy or not feeding well.
Who Is Most at Risk of Severe COVID-19?
While anyone can become unwell with COVID-19, risk of severe disease is higher for:
- Adults aged 75 and over
- People with weakened immune systems due to conditions or treatments such as chemotherapy, high-dose steroids or transplant immunosuppression
- People with certain long-term conditions including chronic lung disease, heart disease, diabetes, chronic kidney or liver disease and some neurological conditions
- Residents of care homes for older adults
- People who are pregnant, who may be more vulnerable to some respiratory infections
This does not mean younger, otherwise healthy adults have no risk. Severe illness can occur at any age, but it is less common.
How Long Does XFG COVID Last?
For most people, COVID-19 symptoms improve within a few days to two weeks. A sore throat and cough can linger longer. Some people take several weeks to return to full energy.
There is no reliable evidence that XFG has a distinct recovery time compared with other Omicron variants. How long symptoms last depends more on age, underlying health, prior immunity and whether complications develop.
A minority of people develop post-COVID condition, often called long COVID, where symptoms such as fatigue, breathlessness, cognitive difficulties or other symptoms persist for more than 12 weeks and cannot be explained by another cause. Current evidence does not show that XFG causes more or less long COVID than other variants. If symptoms persist, contact your GP for assessment and support.
Should People Be Worried About the Stratus Variant?
XFG or Stratus deserves continued monitoring because it is now widespread and has shown a growth advantage over other lineages. The autumn rise in positivity to around 7% and hospital admissions increasing by around 50% in September illustrates why surveillance continues.
However, both UKHSA and WHO have stressed that there is no current evidence that XFG causes more severe disease than other circulating variants, and overall activity remains low compared with previous pandemic peaks. Proportionate precautions, vaccination for those eligible, and early medical advice for those at risk remain the most effective approach.
As with all respiratory viruses, patterns may change, so following official updates rather than unverified claims on social media is important.
Frequently Asked Questions
What is the XFG COVID variant?
XFG is a recombinant Omicron-derived lineage formed from LF.7 and LP.8.1.2. Its earliest sample was collected on 27 January 2025. It is nicknamed Stratus in informal use and has been designated a Variant Under Monitoring by WHO since 25 June 2025. It is now the most common variant in recent UK sequencing data.
What are the first symptoms of Stratus COVID?
Early symptoms are similar to other COVID variants and often include sore throat, hoarse voice, cough, fever, fatigue, headache and a blocked or runny nose. Some people report muscle aches or digestive symptoms. There is no specific symptom that reliably identifies Stratus on its own.
Does XFG cause a particularly painful sore throat?
Many people with XFG report a sore throat, sometimes described as painful or scratchy, and some report hoarseness. These symptoms have also been common with other variants. There is no scientific evidence that a painful sore throat is unique to XFG or can be used to diagnose the variant without testing.
Is the Stratus COVID variant more dangerous?
Based on WHO and UKHSA assessments as of October 2026, there is no evidence that Stratus causes more severe disease, hospitalisation or death than other circulating variants. It has spread widely, which can increase total hospital admissions, but this does not mean it is inherently more dangerous for an individual. Vulnerable groups remain at higher risk from COVID-19 in general.
Can you catch XFG after a previous COVID infection?
Yes. Protection against infection declines over time and new variants can partially evade prior immunity. Previous infection or vaccination still helps protect against severe illness, but reinfection with XFG remains possible.
Do current COVID vaccines protect against XFG?
Vaccines are expected to continue protecting against severe outcomes from XFG, though protection against mild infection may be reduced over time. The UK autumn 2026 vaccine has been formulated to target circulating variants and is offered to those aged 75 and over, care home residents and immunosuppressed people aged 6 months and over. Eligible groups are strongly encouraged to take up the offer.
How long do XFG COVID symptoms usually last?
Most people recover within a few days to two weeks, although cough and fatigue can persist longer. There is no evidence of a variant-specific duration for XFG. If symptoms last beyond 12 weeks, this may be considered post-COVID condition and should be discussed with a GP.
Medical disclaimer: This article is for information purposes and does not constitute medical advice. For personal medical advice, contact your GP, NHS 111 or your specialist team. Guidance may change; check UKHSA and NHS websites for the latest official information.
Dr. Samuel Kemp is a Consultant Physician at the Royal Brompton Hospital with specialist expertise in respiratory medicine, including lung cancer, COPD, and advanced interventional bronchoscopy.