There is no concept of incubation period for tuberculosis infection, and the speed or severity of symptoms is related to the patient’s own immunity. Tuberculosis is a chronic disease with no latency period. Patients who are infected with tuberculosis for the first time, if they have a strong immune system or have antibodies to tuberculosis, the body can clear the tubercle bacilli, leaving no symptoms or only foci of calcification in the lungs, often without clinical symptoms. In patients with lower immunity, this may lead to primary TB, commonly in children. In adults, clinical symptoms may not appear immediately after TB infection, but may become apparent several years after infection. In conclusion, TB infection is related to the immune status of the patient. Patients with deficient or low immunity, the elderly and children with low immunity are susceptible to infection and care should be taken to avoid contact with TB patients.