Influenza A viruses, also known as influenza A viruses, are contagious and highly pathogenic, causing respiratory infections, pneumonia, and other diseases. Influenza viruses belong to the Orthomyxoviridae family, and can be categorized into influenza A (type A), B (type B), and C (type C) depending on the antigenicity of the proteins within the virus. Recent reports have suggested the existence of influenza D (D) viruses. Influenza C viruses cause only mild upper respiratory tract infections. Influenza A and B viruses, on the other hand, can cause many serious illnesses, with the influenza A virus being the most dangerous to human health. Infections can include lower respiratory tract infections, pneumonia, and meningitis, which can be manifested by symptoms such as coughing, fever, and respiratory distress with chest pain, and in severe cases can lead to serious injuries such as acute respiratory distress syndrome, or even life-threatening injuries. Vaccination is an important measure to prevent influenza A and other influenza viruses, and it is recommended that those who meet the conditions for vaccination be actively vaccinated; Influenza A virus is contagious after infection, and it is recommended to go to the fever clinic of hospitals when symptoms such as the above fever occur.