Viral colds are a common illness that people may get at some point in their lives. A viral cold is caused by a viral infection, an infection of the upper respiratory tract caused by a viral infection. A viral cold is not a disease caused by a cold virus, so to speak, it is not a disease, and generally includes the common cold, influenza and viral pharyngitis. Influenza (flu) is transmitted through the nasal cavity mainly through air or hand contact with the flu virus. The common cold is an infection of the upper respiratory tract caused by respiratory syncytial virus, rhinovirus, adenovirus, coronavirus and parainfluenza virus. The common cold is very weakly contagious and usually develops individually and does not lead to a collective outbreak epidemic, and it is only when the body’s resistance decreases that it becomes susceptible to the disease. Influenza is an acute respiratory infection caused by influenza viruses, including influenza A virus, influenza B virus, and influenza C virus. Influenza is transmitted by droplets when a person coughs or sneezes. Influenza is highly contagious, the transmission route is not easy to control, the speed of transmission, the spread of a wide range, it is easy to lead to large-scale outbreaks of epidemic, it used to be every few years to outbreaks of epidemic, the danger is great, before because of the flu died a lot of people. In short, viral flu is not a terrible disease now, and influenza can be prevented by vaccination against influenza.