Influenza (influenza for short) is an acute respiratory infection caused by influenza viruses. Influenza viruses are divided into three types: A, B and C. Influenza A viruses are divided into many subtypes. Influenza A viruses often cause worldwide pandemics, while influenza B viruses often cause localized outbreaks and influenza C viruses mainly appear in circulation. Influenza viruses mainly invade the respiratory tract and do not generally enter the bloodstream, but their toxins have a wide range of toxic effects on organs throughout the body. The most significant epidemiological features of influenza are sudden outbreaks, rapid spread, wide spread, and certain seasonality. The annual peak of influenza activity in northern China generally occurs from the end of November to the end of February of the following year, while in the south it occurs mostly in the winter and summer. Influenza usually stops naturally after 3 to 4 weeks of epidemic. Clinical manifestations Influenza can be classified into simple, pneumonic, toxic and gastrointestinal types according to clinical manifestations. Influenza usually has an acute onset with toxic symptoms such as chills, high fever, headache, dizziness, generalized aches and pains, and fatigue, and may be accompanied by respiratory symptoms such as sore throat, runny nose, lacrimation, and cough. In a few cases, there are gastrointestinal symptoms such as loss of appetite, abdominal pain, bloating, vomiting and diarrhea. The pneumonia type mostly occurs in patients with pre-existing chronic underlying diseases and in children under 2 years of age, and is characterized by high fever, irritability, dyspnea, coughing up blood sputum and obvious cyanosis within 24 hours after the onset of the disease. These symptoms may worsen progressively, and the application of antibacterial drugs is ineffective. The course of the disease is 1 week to more than 1 month, and most patients can gradually recover, but they can also die within 5-10 days due to respiratory and circulatory failure. Influenza generally has a good prognosis and often resolves spontaneously within a short period of time, but infants, the elderly and those with combined chronic underlying diseases have a poorer prognosis. Individual patients can be complicated by paranasal sinusitis, otitis media, laryngitis, bronchitis and pneumonia. Diagnosis 1. Suspected cases: with epidemiological history and relevant clinical manifestations. During the epidemic season, a large number of patients with upper respiratory tract infection appear in one unit or area; there is a significant increase in patients with upper respiratory tract infection in hospital outpatient clinics and emergency departments, and patients with the above clinical manifestations should be suspected of influenza. Routine auxiliary examination shows that the total peripheral blood leukocyte count is not high or low, and the lymphocyte count is relatively increased, both of which may decrease in severe patients. Chest X-ray examination of severe patients may show unilateral or bilateral pneumonia, and a few may be accompanied by pleural effusion. 2.Confirmed case: If the suspected case is positive by further laboratory examination, including virus antigen, virus isolation and serological examination, it is a confirmed case. Treatment 1. Early application of anti-influenza virus drugs: anti-influenza virus drugs should be applied within 1~2 days after the onset of the disease to achieve the best efficacy. At present, anti-influenza virus drugs include ion channel M2 blockers and neuraminidase inhibitors. 2.Strengthen supportive treatment and prevent complications: Since influenza mostly has high fever and high consumption, it is necessary to pay attention to rest, drink more water, pay attention to nutrition, and the diet should be easy to digest. More attention should be paid to children and elderly patients, and complications should be closely observed and monitored. If there is clear or sufficient evidence suggesting secondary bacterial infection, antibiotic treatment should be considered. Commonly used antibiotics include macrolides, β-lactamides or fluoroquinolones. 3.Rational application of symptomatic drugs: If the disease lasts more than 2 days or there is no condition to apply antiviral drugs, symptomatic treatment is available. Such as the application of antipyretic drugs, drugs to relieve congestion of the nasal mucosa and cough expectorant drugs. Aspirin or aspirin-containing drugs and other salicylic acid preparations are contraindicated in children. In the case of influenza in the elderly and organ insufficiency, special attention should be paid to the protective treatment of important organ functions, such as appropriate amount of oxygen, maintaining airway patency, improving myocardial blood supply, etc. 4, Chinese medicine treatment: early medication, evidence-based treatment, according to the evidence can be selected to clear heat, detoxification, dampness, support, eliminate evil and other different treatment rules and prescriptions and proprietary Chinese medicine. Prevention 1. isolate patients, and strengthen ventilation and air disinfection in public places during the epidemic. 2.Reduce large gatherings and group activities during the epidemic, and contact persons should wear masks. 3.Vaccination against influenza: This is the main method to prevent influenza. During the influenza season, vaccination is given to high-risk groups and medical personnel who are susceptible to influenza, and the influenza virus vaccination takes 6-8 weeks to have an immune preventive effect. High-risk groups include: people aged >65 years; people with chronic respiratory or cardiovascular diseases, children aged >6 months; people with renal dysfunction; people with immune suppression; pregnant women above the middle of pregnancy, etc. 4. Application of anti-influenza viral drugs: When an influenza outbreak is clearly or suspected in a particular department, prophylactic treatment with amantadine, amantadine or oseltamivir is given to non-influenza patients and medical personnel who have not been vaccinated for a period of 2 weeks or 1 week after the end of the influenza outbreak.