ObjectiveTo analyze the clinical features, laboratory examination, imaging findings, treatment and outcome of influenza A H1N1 virus infection in China, so as to improve the clinicians' understanding of the disease.MethodsOne patient with influenza A H1N1 pneumonia was reported in this hospital. The databases of CNKI, VIP network and Wanfang data were systematically consulted. After removing the duplicate and deleting the incomplete literature published between January 1989 and August 2019, 62 literatures were included, involving 880 patients. Hence, 881 patients in total were included. The clinical manifestations, laboratory examination, imaging manifestations, treatment and prognosis were analyzed.ResultsThere were 477 males and 404 females, aged from 50 days to 86 years old, with an average age of (20.4 ±10.0) years. The most common clinical symptoms were fever (99.4%, 876/881), followed by cough (85.0%, 749/881), expectoration (38.1%, 336/881), sore throat (37.0%, 326/881) and dyspnea (33.7%, 297/881), asthenia and general pain (33.5%, 295/881) and so on. Laboratory examination in the leukocyte decreased in 249 patients (28.3%), neutrophil increased in 143 patients (16.2%) and leukocyte increased in 141 patients (16.0%). Myocardial injury was found in 370 patients (42.0%), liver injury in 303 patients (34.4%) and renal insufficiency in 84 patients (9.5%). The main imaging manifestations were spotted, patchy or flaky shadows (41.8%, 362/866) in varying degrees, with consolidation shadows (19.3%, 167/866), thickening of lung texture (11.3%, 98/866), ground glass shadows (4.5%, 39/866), and pleural effusion (5.5%, 48/866). The most common treatments were anti-virus, anti-infection, anti-inflammation, mechanical ventilation and symptomatic support. Comprehensive treatment resulted good effects. There were 37 deaths and the mortality rate was 4.2%. The main cause of death was respiratory failure.ConclusionsInfluenza A H1N1 virus infection is a preventable, controllable and treatable infectious disease, which is similar to the general influenza virus. After active comprehensive treatment, most of the influenza A (H1N1) can be cured and the prognosis is benign.