Clinical characteristics of the 2019 novel coronavirus Omicron variant infected cases / 中华传染病杂志

ABSTRACT

Objective:To investigate the clinical characteristics and prognostic factors of 2019 novel coronavirus (2019-nCoV) Omicron variant infected cases.Methods:A total of 987 coronavirus disease 2019 (COVID-19) adult imported cases admitted to Shanghai Public Health Clinical Center, Fudan University from July 1, 2021 to January 6, 2022 were recruited. The cases were divided into Omicron group (193 cases) and non-Omicron group (794 cases) according to the genotype of the virus. The clinical data, imaging examination and laboratory results of two groups were collected and compared. Chi-square test and Mann-Whitney U test were used as statistical methods. Multiple linear regression analysis was used for multiple linear regression analysis. Results:The majority of patients in Omicron group were 18 to 30 years old, accounting for 51.3%(99/193), which was higher than 31.4%(249/794) in non-Omicron group. The difference was statistically significant ( χ2=52.75, P<0.001). The proportion of mild cases in Omicron group was 88.6%(171/193), which was higher than 81.6%(648/794) in non-Omicron group. The difference was statistically significant ( χ2=5.37, P=0.021). Cases with symptoms were more common in Omicron group than those in non-Omicron group (60.1%(116/193) vs 29.1%(231/794)), and the difference was statistically significant ( χ2=65.49, P<0.001), with the main clinical manifestations of sore/itchy throat, fever and cough/expectoration. The proportion of cases with pulmonary computed tomography (CT) imaging manifestations at admission in Omicron group was 13.0%(25/193), which was lower than that in non-Omicron group (215/794, 27.1%). The difference was statistically significant ( χ2=16.83, P<0.001). The proportion of cases with 2019-nCoV IgG positive at admission was 47.7%(92/193) in Omicron group, which was lower than 61.1%(485/794) in non-Omicron group, and the difference was statistically significant ( χ2=11.51, P<0.001). The hospitalization time of Omicron group was 20.0 (16.0, 23.0) d, which was longer than that of non-Omicron group (14.0 (10.0, 22.0) d), and the difference was statistically significant ( Z=-7.42, P<0.001). Multiple linear regression analysis showed that the time of hospitalization of cases with 2019-nCoV IgG positive at admission was shorter, while that of the cases with fever in Omicron group was longer (both P<0.050). Conclusions:The main clinical characteristics of cases with Omicron variant are fever and upper respiratory symptoms. Their pulmonary CT imaging manifestations are less, and the time of hospitalization is slightly longer. The time of hospitalization and the virus clearance time in Omicron variant infected cases with 2019-nCoV IgG positive at admission and not presented with fever are both shorter.