Influenza A is mainly transmitted through respiratory tract and contact. Influenza A is an acute respiratory disease caused by infection with influenza A virus, also known as influenza A. It is mainly transmitted through droplets via the respiratory tract as well as mucous membrane contact, and is generally contagious within 1-7 days of onset of the disease, and is most contagious in about 3 days of infection. Influenza A also has a certain degree of prevalence, people of all ages can be infected, patients can appear fever, runny nose, muscle aches, sore throat, headache, weakness and other symptoms, infected with influenza A should go to the hospital in a timely manner to actively treat. Everyday to do a good job of prevention, reduce crowd gathering, maintain good hygiene habits, flu vaccination is the most effective way to prevent influenza.