Influenza H3N2 refers to Influenza A H3N2. Patients with Influenza A H3N2 can have fever, cough, headache, vomiting, diarrhea and other symptoms, and in severe cases, it can be followed by pneumonia or even death. Influenza A H3N2 is contagious. Influenza A H3N2 is a respiratory disease caused by the influenza A H3N2 virus, which is contagious and spreads mainly through the respiratory tract. Patients infected with Influenza A H3N2 may have fever, cough, sore throat, headache, chills, body aches, fatigue and other symptoms, and some patients may also have gastrointestinal symptoms such as nausea, vomiting and diarrhea. In severe cases, complications such as pneumonia and respiratory failure may follow, even leading to death, especially for people with poor immunity and many underlying diseases. An effective preventive measure against Influenza A (H3N2) is through vaccination. In particular, frail elderly people and children with low resistance should be vaccinated as much as possible to prevent influenza. In addition, during the Influenza A (H3N2) pandemic, attention should be paid to maintaining indoor ventilation, ensuring adequate sleep and practicing good personal hygiene, which are also effective in preventing the influenza virus from attacking. In areas where Influenza A (H3N2) outbreaks occur, once symptoms such as fever, cough, headache, etc. appear, one should consult a doctor in a timely manner and be properly isolated, and should actively cooperate with the doctor’s treatment.