<i>Research background</i>: Since the gradual liberalization of the epidemic in China in November 2022, economic activities have gradually resumed, the incidence of COVID-19 admitted to our hospital has gradually decreased, the symptoms and the toxicity have gradually decreased. <i>Objective</i>: By analyzing the research and analysis of the treatment of patients infected with COVID-19 infection in the Third People's Hospital of Sichuan Province from December 2022 to February 2023, can help to understand the clinical manifestations of COVID-19 virus infection after the opening of the epidemic in China, and guide patients to standardize medical treatment. The follow-up research and treatment of COVID-19 after the epidemic is released for reference. <i>Research method</i>: inclusion standard: patients with COVID-19 pharyngeal swab test positive. We used the "Case Information System and Prevention and Control System" to carry out statistical analysis and retrospectively study of theCOVID-19 infection since the opening of the epidemic. <i>Research results</i>: In this study, the total number of outpatient visits to respiratory medicine in the Third People's Hospital of Sichuan Province from December 1, 2022 to February 28, 2023 was 4,582 people/90 days. The total hospitalization rate was 7.88% (361/4582), due to the COVID-19 infection is 1.55% (71/4582); men account for 0.94%, women account for 0.61%, and the total mortality rate after hospitalization is 1.10% (4/361), and the total mortality rate of patients after the novel COVID-19 infection is 0. 55% (2/361), as shown in Figure 1, Figure 2 and Figure 3. After national vaccination, the main symptoms of patients infected with COVID-19 are fever, soreness all over the body, mainly lung invasion changes, the number of severe patients and respiratory failure is small, indicating that its toxicity is reduced. With the largest number of cases in the 50-75-year-old group, accounting for 36.61% (26/71) and a mortality rate of 2.82% (2/71). Common with respiratory failure and abnormal liver function. The more complications, the older age, the more days of hospitalization, and the higher cost of hospitalization<i>. Conclusion: </i>Since the vaccination against the COVID-19 in China, the mortality rate due to the COVID-19 in our hospital is low, and the incidence of severe clinical manifestations is low, which shows that the toxicity of COVID-19 infection has gradually decreased with COVID-19 vaccination. This study found that the older patients with multiple complications, the more hospitalization days, the higher the cost of hospitalization. For elderly patients with a variety of complications and complications, recommended to be hospitalized in time.