摘要目的:探索珠海市新型冠状病毒(2019-nCoV)奥密克戎(Omicron)变异株BA.1和BA.2亚型感染者的临床特征。方法:纳入2022年1月13日至3月8日中山大学附属第五医院收治的122例2019-nCoV Omicron变异株感染者，其中成人病例79例(BA.1亚型23例，BA.2亚型56例)，儿童病例43例(BA.1亚型19例，BA.2亚型24例)。比较BA.1亚型和BA.2亚型病例不同年龄组的临床表现、实验室检查指标、病毒载量、疫苗接种和感染类型的差异。计量资料采用Mann-Whitney U检验或Kruskal-Wallis H检验，计数资料采用 χ2检验或Fisher确切概率法。 结果:在成人Omicron变异株感染者中，BA.2亚型感染者基线病毒载量比BA.1亚型高[7.64(6.92，8.55) lg拷贝/mL比6.64(6.04，7.34) lg拷贝/mL， Z＝-3.022， P＝0.003]，且无症状感染者和轻型患者比例更高，普通型患者比例更低( χ2＝8.052， P＝0.012)，BA.1亚型感染者肺部出现炎症比例(6/23，26.1%)高于BA.2亚型感染者(2/56，3.6%)( χ2＝6.776， P＝0.009)。在儿童病例中，BA.2亚型感染者发热比例(16/24，66.7%)高于BA.1亚型感染患儿(5/19，26.3%)，淋巴细胞计数降低百分比(17/24，70.8%)亦高于BA.1亚型患儿(1/19，5.3%)( χ2＝6.910和18.734， P＝0.009和 P<0.001]。与成人病例相比，BA.2亚型感染患儿发热比例更高[(16/24，66.7%)比(19/56，33.9%)， χ2＝7.317， P＝0.007)]。成人和儿童BA.2亚型鼻拭子两周内病毒载量均呈先上升后下降趋势，下降幅度比BA.1亚型更快。 结论:成人2019-nCoV Omicron变异株BA.2亚型感染者入院时基线病毒载量高，早期传染性更强，但病毒载量下降更快，儿童BA.2亚型感染者发热比例和淋巴细胞计数降低百分比更高，提示BA.2亚型防控形势更加严峻。

abstractsObjective: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.