Objective:To explore the clinical characteristics of patients infected with 2019 novel coronavirus (2019-nCoV) Omicron variant in Zhuhai City.Methods:A retrospective study was conducted to compare the clinical characteristics of patients infected with 2019-nCoV Omicron variant (Omicron variant group, 39 cases) from January 13 to January 25, 2022, and those infected with 2019-nCoV non-Omicron variant (non-Omicron variant group, 98 cases) from January 17 to February 17, 2020, in the Fifth Affiliated Hospital of Sun Yat-sen University. Statistic methods were used by Mann-Whitney U test, chi-square test and Fisher exact probability test. Results:Among adults, the age of 21 patients in Omicron variant group was younger than that of 93 patients in non-Omicron variant group (34.0(26.0, 40.5) years vs 50.0(36.0, 62.0) years, Z=-3.81, P<0.001). Patients with underlying diseases in Omicron variant group were fewer than those in non-Omicron variant group (4.8%(1/21) vs 31.2%(29/93), χ2=6.17, P=0.013). The clinical classification of the Omicron variant group was mainly mild (71.4%(15/21)) or common type (28.6%(6/21)), while the non-Omicron variant group was dominated with common type (57.0%(53/93)) and severe type (23.7%(22/93)), and the clinical classification of the two groups had statistically difference ( χ2=31.79, P<0.001). The time of positive nucleic acid in Omicron variant group was longer than that in non-Omicron variant group (14.0(10.5, 16.5) d vs 8.5(4.0, 12.0) d, Z=-3.56, P<0.001). The proportion of pneumonia in Omicron variant group was less than that in non-Omicron variant group (28.6%(6/21) vs 86.0%(80/93), χ2=30.52, P<0.001). Differences were all statistically significant. There was no significant difference of the clinical characteristics in pediatric patients, but the proportion of children infected with 2019-nCoV Omicron variant was significantly higher than that infected with 2019-nCoV non-Omicron variant (46.2%(18/39) vs 5.1%(5/98), χ2=33.65, P<0.001). Conclusions:Adults infected with 2019-nCoV Omicron variant in Zhuhai City present with milder clinical symptoms, less proportion of pneumonia, but the time of positive nucleic acid is longer. The clinical characteristics of children infected with 2019-nCoV Omicron variant are not specific, while the proportion of children infected with 2019-nCoV Omicron variant is significantly higher.

Objective:To analyze the clinical characteristics of patients infected with 2019-nCoV Omicron variants BA.1 and BA.2 in Zhuhai city.Methods:A retrospective study was conducted to compare clinical characteristics of patients infected with 2019-nCoV Omicron variants BA.1 and BA.2, who were admitted in the Fifth Affiliated Hospital of Sun Yat-sen University during January 13 to March 8 2022. The Mann-Whitney U-test or Kruskal-Wallis H test was used for quantitative data, and the χ2 test or Fisher’s exact test was used for qualitative data. Results:Among 122 patients infected with the Omicron variant, there was 79 adults (BA.1 23 cases, BA.2 56 cases) and 43 children (BA.1 19 cases, BA.2 24 cases). In adults, patients infected with BA.2 sub-variant had a higher baseline viral loads at admission than BA.1 infected patients [7.64(6.92, 8.55) lg copies/mL vs. 6.64(6.04, 7.34) lg copies/mL; Z=-3.022, P=0.003]; compared to BA.1 patients, BA.2 patients had a higher proportion of mild and asymptomatic cases and a lower proportion of common infection cases ( χ2=8.052, P=0.012); the proportion of patients with pneumonia imaging changes in BA.1 patients was higher than that in BA.2 infected patients [(6/23, 26.1%) vs. (2/56, 3.6%); χ2=6.776, P=0.009). In children, the rate of fever in BA.2 group was higher than that in BA.1 group [(16/24, 66.7%) vs. ( 5/19, 26.3%); χ2=6.910, P=0.009); the proportion of patients with reduced lymphocyte counts in BA.2 group was higher than that in BA.1 group [(17/24, 70.8%) vs.(1/19, 5.3%); χ2=18.734, P<0.001). Compared with adult cases, children with BA.2 sub-variant infection had higher fever rate [(16/24, 66.7%) vs. (19/56, 33.9%); χ2=7.317, P=0.007). The viral loads of daily nasal swabs in BA.2 infected patients increased first and then decreased in both adults and children, with a greater decrease than BA.1 during the first two weeks. Conclusions:Compare with 2019-nCoV Omicron variant BA.1, BA.2 has a higher baseline viral loads in adults, which means much more contagious in the early stages. But the viral load drops faster in BA.2 infected patients. In children, BA.2 patients are more likely to have fever and reduced lymphocyte counts, which indicates that the prevention and control of 2019-nCoV Omicron sub-variant BA.2 is more difficult.