The survival of HIV patients varies widely, depending on the stage of infection and the availability of treatment. If a patient is on regular antiviral treatment early on, life expectancy is similar to that of a normal person. However, if they enter the AIDS stage, their survival period is usually 1-1.5 years under normal circumstances. The length of time between HIV infection and the actual stage of AIDS, the incubation period, is indeterminate, ranging from half a year to 10 or even 20 years. Most infected patients in China discover their HIV infection only after symptoms appear, when they have already entered the AIDS stage. However, if the disease is detected during the incubation period and the patient actively takes antiviral drugs in cooperation with the doctor, immune reconstruction can be achieved, and as long as no opportunistic infections or other complications occur, life expectancy is usually no different from that of a normal person. AIDS is an extremely critical disease and is transmitted through blood, sexual contact and mother-to-child transmission.