Influenza is mainly spread by droplets through the respiratory tract, but can also be spread indirectly through contact with contaminated hands and daily utensils. Influenza, or influenza, is an acute respiratory infection caused by the influenza virus. The main source of infection is people with influenza, followed by people with hidden infections. Influenza viruses are generally transmitted from 2 days before the onset of influenza symptoms to about a week after the onset of symptoms. Among them, it is most contagious in the early 2~3 days of the disease. The main route of transmission of influenza is the respiratory tract, often through droplet transmission. It can also be spread partly by indirect contact with contaminated hands, dishes, and other daily utensils. People are generally susceptible to influenza viruses, and although they may acquire immunity to the same subtype after infection, there is no cross-immunity between different subtypes, and the disease may recur. If you feel unwell, it is recommended that you seek prompt medical attention.