Epidemiological characteristics of patients from fever clinics with COVID-19 epidemic in 2022 in Shanghai, China.

Abstract The outbreak of COVID-19 in Shanghai, China, in March 2022, was caused by the Omicron variant. The epidemic lasted for more than 3 months, and the cumulative number of infected people reached 626,000. We aimed to investigate the impact of clinical factors on disease outcomes in patients with COVID-19. In this study, we collected fever clinics confirmed Omicron variant infection cases, analyzed their population and laboratory diagnostic characteristics, and provided theoretical support for subsequent epidemic prevention and control. The results of this study show that the COVID-19 vaccine can protect against Omicron variant infection, and more than 50% of infected people have not been vaccinated before. Compared with the epidemic in Wuhan 2 years ago, most of the patients in the hospital in the Shanghai epidemic had underlying diseases (P < 0.05). In the comparison between patients with Omicron variant epidemic in Shanghai and patients with respiratory tract infection, there was no significant difference in N%, L%, monocytes, eosinophils, RBC, HB, PLT, etc. (P > 0.05). People over 60 years old and with underlying diseases were the risk factors for pneumonia [HR: 14.62 (5.49–38.92), P < 0.001; HR = 5.29 (2.58–10.85), P < 0.001, respectively]. But vaccination was a protective factor [HR = 0.24 (0.12–0.49), P < 0.001]. In summary, it was confirmed that the vaccine has an effect on the infection of Omicron variant strains and the protection against pneumonia. The virus damage of Omicron variant strains has a significant downward trend compared with 2 years ago.