RESUMEN
Objective: To analyze the epidemiological and clinical characteristics of patients infected with different subtype of 2019-nCoV Omicron variants BA.2 and BA.5 in Xi'an city. Methods: A retrospective observational study was conducted to collect data of 168 patients infected with Omicron variant admitted to the designated hospital for COVID-19 charged by Xi'an Chest Hospital during 2022. Data were collected including epidemiological, clinical features, laboratory and viral load, and the difference between BA.2 and BA.5 subtype was analyzed. Results: A total of 168 patients were admitted, including 122 cases infected with BA.2 subtype, and 46 cases infected with BA.5 subtype. Patients infected with BA.2 subtype had a higher rate of cough than BA.5 subtype (43.44%â¶23.91%; P=0.021). Compared with the Omicron variant BA.2, patients infected with BA.5 subtype had a higher proportion of asymptomatic and mild infections (89.13%â¶68.85%; P<0.001), higher rate of vaccination (95.66%â¶68.03%; P<0.001), shorter time to nucleic acid negative conversion (8.62; P=0.047), and a higher viral load at admission (P=0.005, P=0.017). Conclusions: The Omicron variant is extremely infectious with aggregated onset, but its clinical symptoms are mild. The vaccine, especially the booster vaccination, remains effective in preventing severe stage progression and improving prognosis in patients with Omicron variant infection.