Influenza belongs to category C infectious disease according to the Infectious Disease Control Law, and to respiratory infectious disease according to the transmission route. Influenza is an acute respiratory infection caused by the influenza virus, which is very contagious and can be spread through respiratory droplets or indirectly through virus-contaminated objects. Influenza viruses are the most common viruses causing upper respiratory tract infections, and can be divided into three types: A, B, and C. Influenza A is the most susceptible to mutation, making the population generally susceptible, with a high incidence rate, and generally occurs once every few years as an epidemic or outbreak. The symptoms of systemic toxicity, such as fever, headache and malaise, are relatively obvious. Influenza is generally self-limiting, with self-recovery in 3-5 days, but a few patients may develop toxic or pneumonic forms, which can cause exacerbation of the disease and respiratory failure. Influenza vaccination can be used to prevent the onset of influenza and is particularly suitable for people in critical or high-risk groups.