Influenza vaccine is to prevent influenza virus, which can cause influenza, is an acute respiratory tract infection and belongs to category C infectious disease. Influenza is prevalent in China in winter and spring, with clinical manifestations of high fever, malaise, headache, cough, generalized muscle pain and other symptoms of systemic toxicity, and light respiratory symptoms. Influenza viruses are prone to mutation, highly contagious, with widespread susceptibility and high incidence, and have historically caused many outbreaks around the world, making it an important public health issue of global concern. Influenza is spread through droplet and contact transmission and is very contagious and spreads quickly. It is usually self-resolving in 3-14 days, but can be life-threatening in severe cases, and can cause outbreaks in crowded places such as schools, childcare facilities and nursing homes.