The virus requires special attention due to the risk it poses to children, the elderly, and patients with chronic diseases. The emergence of a new variant is associated with antigenic drift - the gradual accumulation of mutations that change the properties of the virus. Due to these changes, it differs from the variants that circulated in previous seasons. ## ## What is dangerous about Hong Kong flu The A(H3N2) virus is highly contagious and can cause severe symptoms. In the 2025–2026 season, according to the provided data, it accounted for about 80% of flu cases at the peak of illness. The danger is not only related to high fever and severe weakness. Possible complications include pneumonia and bronchitis, as well as myocarditis, which is inflammation of the heart muscle. The illness can also be accompanied by otitis, especially in children. In childhood, there is also a risk of false croup - swelling of the larynx that can obstruct breathing. ## ## Who is at risk The most vulnerable are children under two years old, elderly people over 65, and pregnant women. There is also an increased risk of severe illness for people with chronic heart, lung, and kidney diseases, as well as for patients with diabetes. How to recognize the symptoms Influenza caused by the A/Darwin virus usually begins suddenly. Within the first day, the temperature can rise to 38–40 °C, and the illness is accompanied by pronounced weakness, headache, eye pain, and body aches. A characteristic symptom is a dry cough. Sore throat and nasal congestion are also possible. High fever and a sharp deterioration in well-being may indicate influenza, but on their own do not allow for the identification of a specific strain. In cases of difficulty breathing, chest pain, or a sudden worsening of condition, urgent medical assistance is necessary.
