The immune system is an important defense system in the body, when the patient’s immunity is reduced may be frequent infections, generally common infection sites for the respiratory tract, gastrointestinal tract, skin, etc., the patient may have a sore throat, diarrhea, itchy skin and other symptoms. 1. Respiratory tract infections: After the immunity is reduced, it is easy to be repeatedly infected with influenza virus, respiratory syncytial virus and other pathogenic bacteria, and the patient is prone to sore throat, cough, fever, chills, nasal congestion and other symptoms. 2. Gastrointestinal infections: after immunity decline, the gastrointestinal tract of patients may be infected by Escherichia coli, enteric adenovirus and other pathogenic bacteria, and patients are prone to diarrhea, abdominal pain, bloody stools and other symptoms. 3. Skin infections: After immunity decline, skin contact with staphylococcus, herpes virus, Candida albicans and other pathogenic bacteria may lead to infections, which may cause itching, swelling and pain of the skin, and some patients may also have blisters, pimples and other symptoms. In case of immunocompromised conditions, patients are advised to seek medical advice as early as possible and take appropriate interventions if necessary to avoid deterioration of the condition.