TAMPA, Fla., Nov. 20, 2025 (GLOBE NEWSWIRE) -- The Global Virus Network (GVN), a coalition of leading human and animal virologists in more than 40 countries dedicated to advancing pandemic preparedness through research, education and training, and global health solutions, today issued a statement on the emergence of a new influenza A (H3N2) variant known as H3N2 subclade K that is spreading rapidly and may contribute to a more intense flu season worldwide. Public health agencies in the United Kingdom, several countries across Europe, Japan, and parts of North America have reported sharp week-over-week increases in cases driven by this subclade, signaling accelerated global spread.
GVN experts report that H3N2 subclade K represents an evolved branch of the seasonal H3N2 viruses that circulate each year. The strain has accumulated several mutations that may increase transmissibility and enable partial immune escape, contributing to earlier and more widespread influenza activity in multiple regions. Surveillance data show particularly rapid growth in the UK and Western Europe, with rising detections in Canada and the northeastern United States, as well as increased influenza activity across East Asia. Although this year’s vaccine is imperfectly matched to the new variant, available evidence indicates it still provides meaningful protection, particularly against severe illness and hospitalization.
Peter Palese, PhD, pioneering influenza virologist, GVN Center of Excellence director at the Icahn School of Medicine at Mount Sinai, and National Academy of Sciences member, explained that “this new H3N2 subclade K variant is not an entirely new virus but a further evolved form of the influenza strains we confront every year. What we are seeing is genetic drift, meaning the virus has gradually accumulated small mutations in its surface proteins over time. These subtle changes can make it harder for the immune system to fully recognize the virus, even in people who were previously infected or vaccinated. Even with this drift, vaccination remains our most effective measure to prevent severe disease and reduce pressure on hospitals, which is why continued investment in influenza research, including efforts toward universal vaccines, is so important.”
Building on this assessment, Sten H. Vermund, MD, PhD, GVN chief medical officer and dean of the University of South Florida College of Public Health, noted that “influenza’s evolution this season highlights the reality that viral threats never occur in isolation. We are monitoring not only this drifted H3N2 subclade K variant but also ongoing avian influenza activity, including infections caused by H5 viruses in both animals and humans. This moment calls for a renewed commitment to vaccine uptake and early antiviral treatment. Global vigilance is supported by strong surveillance systems and responsible communication.”
What the New Strain Means for Global Health
• H3N2 subclade K is a mutated form of circulating H3N2 viruses that is spreading more efficiently and partially evading existing immunity. This pattern of change is known as viral “drift,” in contrast to the more extreme “shift” that can precede pandemic spread.
• Despite the drift, the current seasonal vaccine still offers protection, especially against severe disease.
• Countries reporting the steepest increases include the UK, France, Germany, Japan, and Canada, with additional growth now observed in the northeastern United States.
• Several countries are reporting an earlier and stronger start to flu season, raising concern about increased strain on health systems.
• Avian influenza viruses, including H5 and H9 lineages, continue to cause sporadic human infections, underscoring the need for strong One Health surveillance.
GVN Recommendations
In alignment with its mission to strengthen pandemic preparedness through research, education, and global health solutions, the GVN urges governments, clinicians, and communities to:
• Strengthen influenza vaccination campaigns, particularly for high-risk groups such as older adults, young children, pregnant individuals, people with chronic conditions, and those with weakened immune systems.
• Increase access to rapid diagnostics and early antiviral treatment.
• Enhance integrated One Health surveillance across human, animal, and environmental sectors.
• Invest in next-generation and broadly protective influenza vaccines.
• Maintain timely and transparent data-sharing across regions.
Dr. Vermund emphasized that “influenza teaches us every year that preparedness cannot be seasonal. It must be continuous, globally coordinated, and grounded in science, surveillance, and strong public health systems.”
Media Contact:
Nora Samaranayake
nsamaranayake@gvn.org
About the Global Virus Network
The Global Virus Network (GVN) is a worldwide coalition comprising 90+ Virology Centers of Excellence and Affiliates across 40+ countries, whose mission is to facilitate pandemic preparedness against viral pathogens and diseases that threaten public health globally. GVN advances knowledge of viruses through (i) data-driven research and solutions, (ii) fostering the next generation of virology leaders, and (iii) enhancing global resources for readiness and response to emerging viral threats. GVN provides the essential expertise required to discover and diagnose viruses that threaten public health, understand how such viruses spread illnesses, and facilitate the development of diagnostics, therapies, and treatments to combat them. GVN coordinates and collaborates with local, national, and international scientific institutions and government agencies to provide real-time virus informatics, surveillance, and response resources and strategies. GVN's pandemic preparedness mission is achieved by focusing on Education & Training, Qualitative & Quantitative Research, and Global Health Strategies & Solutions. The GVN is a non-profit 501(c)(3) organization. For more information, please visit www.gvn.org
