What You Need to Know About the Stratus COVID Variant XFG

What You Need to Know About the Stratus COVID Variant XFG

The Stratus strain, scientifically known as XFG (with subvariant XFG.3), is a recombinant variant of COVID-19 from the Omicron lineage. The stratus covid variant is a new variant that has emerged as a dominant strain in several regions. The covid variant Stratus is considered a new strain derived from earlier variants and previous variants of Omicron.

It has become dominant in regions like England due to its rapid spread and immune evasion capabilities. According to surveillance reports and available data, the highest proportion of cases attributed to the Stratus variant has been observed in the South-east Asia Region.

The Stratus strain, scientifically known as XFG (with subvariant XFG.3)

Introduction to the Stratus Variant

The Stratus variant, also referred to as the XFG variant, is a new Covid variant that has been rapidly spreading across multiple regions worldwide. The World Health Organization (WHO) has classified the Stratus variant as a “variant under monitoring” due to its increased prevalence and the potential public health implications it may pose. While the Stratus variant features certain mutations in the spike protein that could help it evade antibodies developed from prior infections or vaccinations, current data indicates that it does not lead to more severe disease or higher disease severity compared to other circulating variants. Health authorities continue to monitor the situation closely at the global level, but the WHO currently assesses the overall risk as low. As with other variants, ongoing surveillance and research are essential to track any changes in the Stratus variant’s behavior or impact.

Key Characteristics

Origin – A “Frankenstein” variant formed from the recombination of LF.7 and LP.8.1.2 strains.

The UK is now grappling with a new ‘Frankenstein’ variant of coronavirus

Dominance – In England, it rose from 10% of cases in May 2025 to ~40% by mid-June 2025. Globally, it accounted for 22.7% of cases by June 22, 2025, with a ~6% daily growth advantage, according to data relating to the global spread and prevalence of the Stratus variant.

Stratus and its subvariant XFG.3 are the two variants currently being closely monitored, with their prevalence outpacing most co-circulating variants in the same regions.

Mutations – Spike protein mutations (e.g., at amino acids 478 and 487) enhance immune evasion.

WHO Status – Designated a “variant under monitoring” on June 25, 2025. Global health risk is low.

Symptoms

The key symptoms and most noticeable symptoms of the Stratus variant include hoarseness (scratchy/raspy voice), which is considered a unique symptom distinguishing it from other Covid strains.

Other common symptoms include:

• Dry cough
• Sore throat
• Fever
• Fatigue
• Muscle aches
• Loss or change in smell/taste
• Shortness of breath
• Runny/blocked nose
• Headache
• Diarrhea
• Loss of appetite
• Nausea

Stratus symptoms often mimic those of the common cold or flu, so testing is important for accurate diagnosis.

Symptoms are generally mild to moderate, with no increased severity compared to other variants. Noticeable symptoms like hoarseness are more apparent in Stratus cases.

Important Note: Stratus (XFG) is distinct from Nimbus (NB.1.8.1), which is linked to a “razor blade” sore throat.

Transmissibility and Immune Evasion

Highly infectious due to spike protein mutations that improve cell binding and immune evasion. Stratus tend to cause mild to moderate symptoms, similar to other Omicron variants.

Declining population immunity (from lower booster uptake and fewer recent infections) may increase susceptibility, potentially causing a new wave, though its scale is uncertain.

Vaccines are expected to remain effective against severe disease, despite partial immune evasion.

According to current evidence, the Stratus variant does not pose an additional public health risk compared to other circulating variants.

Severity, Associated Disease Severity, and Public Health Risk

No evidence of increased severity, hospitalizations, or deaths compared to other Omicron variants. However, there have been reported increases in cases and hospitalizations in some regions. The associated disease severity of the Stratus variant remains comparable to other Omicron variants, with no evidence that it causes more severe illness.

WHO notes rising cases/hospitalizations in some Southeast Asian countries with high XFG prevalence, but severity is comparable to other variants. The overall public health risk is considered low risk, with no significant additional public health risks identified.

UK COVID-19 cases are declining, with 5.4% of tests positive in the week ending June 29, 2025. The proportion of covid cases attributed to the Stratus variant is being closely monitored. Current data do not suggest that the variant leads to increased hospitalizations or more severe outcomes compared to other circulating strains.

Diagnosis and Testing

Diagnosing an infection with the Stratus variant requires a Covid-19 test, which is available through healthcare providers or over-the-counter retailers. Because the symptoms of the Stratus variant can closely mimic those of the regular flu or common cold, such as a sore throat or fatigue, testing is crucial to confirm a coronavirus infection. The UK Health Security Agency (UKHSA) advises anyone experiencing symptoms associated with the Stratus variant—like a scratchy or raspy voice, dry cough, or fever—to take a Covid test promptly. Early diagnosis not only helps individuals manage their health but also supports efforts to prevent further spread of the variant. If you test positive, following recommended isolation procedures is important to protect others in your community.

Prevention and Vaccination

Preventing the spread of the Stratus variant relies on a combination of vaccination, good hygiene, and social distancing. The World Health Organization (WHO) continues to recommend that everyone stay up to date with Covid vaccines, as current data shows that vaccines remain effective at protecting against severe illness caused by the Stratus variant. Health authorities, including experts like Dr. Kaywaan Khan, a Harley Street GP and founder of Hannah London Clinic, stress the importance of prevention and vaccination in reducing the risk of severe outcomes. In addition to vaccination, regular handwashing, maintaining distance from those who are unwell, and avoiding crowded indoor spaces are effective strategies to limit transmission. By following these measures, individuals can help curb the spread of the Stratus variant and protect themselves and others from severe illness.

Recommendations

Testing and Isolation – Test if symptomatic (e.g., hoarseness, fatigue). If positive, isolate until 48 hours after symptoms are mostly gone to prevent spread.

Vaccination – Stay updated with boosters, especially for high-risk groups (aged 75+, care home residents, immunocompromised). UK spring 2025 boosters were offered, with the next round bookable from September 1, 2025, starting October 1.

Precautions – Handwashing, distancing from sick individuals, and good ventilation are effective.

Medical Attention – Consult a GP for worsening symptoms or high-risk conditions. Seek urgent care for severe symptoms (e.g., difficulty breathing, chest pain).

Challenges in Tracking

Reduced testing globally makes it hard to measure Stratus’s true spread and prevalence accurately.

Other Variants

Nimbus (NB.1.8.1) – A recombinant Omicron variant, ~17% of UK cases in June 2025 but declining (7.19% in England). Associated with a “razor blade” sore throat.

Stratus has overtaken Nimbus in England and is expected to dominate globally.

Critical Perspective

Stratus is highly transmissible but not more severe than other Omicron variants. Existing vaccines remain effective against severe outcomes. The “Frankenstein” label and unique symptoms like hoarseness may amplify concern, but the risk is manageable, especially for vaccinated individuals. Dr Kaywaan Khan Harley, a Khan Harley Street GP and Kaywaan Khan Harley Street expert, has commented on the distinctive symptoms and vaccine effectiveness, providing reassurance about the clinical features of the Stratus variant. Dr Alex Allen, a Dr Alex Allen consultant, consultant epidemiologist, and Alex Allen consultant epidemiologist, has provided insights on the mutation patterns and public health implications of the Stratus variant, emphasizing ongoing monitoring and expert oversight. Cosmopolitan UK has also featured expert commentary and health information on the Stratus variant, highlighting the importance of credible sources. According to available evidence, the Stratus variant does not pose a significant additional risk and current vaccines remain effective.

Low testing rates obscure the variant’s spread, a broader surveillance issue. Distinguishing Stratus from Nimbus is challenging without robust clinical data, as symptom reports vary.