Influenza can be classified into three types based on the surface membrane proteins and nucleocapsids: type A, type B, and type C. Type A influenza usually causes major outbreaks in populations. Due to frequent genotypic changes in type A influenza, the general population often lacks immunity against it. Generally, influenza is a legally designated class B infectious disease in the country, and it can be transmitted to normal or healthy individuals through droplets, sneezing, or aerosols. Therefore, if an outbreak occurs, isolation measures should be taken, people should avoid crowded public places as much as possible, and maintain ventilation by keeping windows open, to prevent transmission from infected patients or certain animals.