The time between exposure to a varicella patient and the onset of clinical symptoms is the incubation period for varicella, which is generally 10-21 days, with 14-16 days being the most common. The incubation period of chickenpox is long, and the length of the incubation period is related to the number of viral infections, the body’s immunity, and whether or not it has been vaccinated against chickenpox. If the number of exposure to the virus is large, the body immunity is poor, the patient has not received chickenpox vaccine, for susceptible people, generally 90% will appear onset, and the incubation period is short. If the patient has been vaccinated against chickenpox vaccine, just within the protection period, generally can not develop, or more than the immunization period after the titer of the antibody disappeared, can develop, but the general condition is mild. It should be noted that not only patients with chickenpox are the source of chickenpox infection, but also patients with herpes zoster are the source of chickenpox infection, and contact with patients with herpes zoster may also lead to chickenpox disease.