Delta is a mutated strain of the new coronavirus, characterized by a short incubation period, strong infectiousness, rapid onset, and great difficulty in treatment. After the human body is infected with Delta, most of the patients are latent infection and mild infection, but a small number of patients can develop severe disease in the earliest 3-4 days, and the serious ones can be turned into severe or even critical disease within 24 hours, which need to be admitted to the intensive care unit for treatment. Patients infected with delta onset, the early symptoms may only show drowsiness, fatigue, abnormal sense of smell, or mild muscle aches and pains, etc., with the development of the disease may appear red eyes, sore throat, nasal congestion, runny nose, abdominal pain, diarrhea, rashes and other symptoms. If the patient himself has a chronic disease or poor physical quality, or the onset of the disease is not treated in time, it is likely to develop into a severe disease, and then manifested as respiratory distress, cyanosis, hypoxemia, and so on, and may even have shock, metabolic acidosis, and multi-organ failure, and so on. Therefore, people with symptoms such as drowsiness, fatigue, abnormal sense of smell, and mild muscle pain, especially those with a history of living in high-risk areas or close contact with confirmed patients, must seek medical attention for nucleic acid tests in a timely manner, and those with confirmed diagnosis need to be isolated and treated to avoid deterioration of the condition and affecting the prognosis. Meanwhile, during the process of seeking medical treatment, protective measures should be taken to avoid spreading the disease to others. Vaccination with the new crown vaccine has a certain protective effect on Delta, so it is recommended that people who meet the conditions for vaccination be actively vaccinated. In daily life should also pay attention to personal protection, correctly wear masks, maintain a safe distance, wash hands and disinfect frequently, less crowded places to prevent Delta infection.