Objective: To understand the characteristics and associated factors of viral nucleic acid conversion in children infected with Omicron variant strain of SARS-CoV-2 in Shanghai. Methods: The clinical symptoms, laboratory results and other data of 177 children infected with SARS-CoV-2 who were hospitalized in Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University (designated hospital for SARS-CoV-2 infection in Shanghai) from April 25 to June 8, 2022 were retrospectively analyzed. According to the chest imaging findings, the children were divided into mild and common type groups. According to their age, the unvaccinated children were divided into<3 years old group and 3-<18 years old group. According to the vaccination status, the children aged 3-<18 year were divided into non-vaccination group, 1-dose vaccination group and 2-dose vaccination group. Comparison between groups was performed by independent sample t-test and analysis of variance, and multivariate linear regression analysis was used for multivariate analysis. Results: Among the 177 children infected with Omicron variant of SARS-CoV-2, 96 were males and 81 were females, aged 3 (1, 6) years. The time of viral nucleic acid negative conversion was (10.3±3.1) days. The 177 children were 138 cases of mild type and 39 cases of common type. Among the children aged 3-<18 years old, 55 cases were not vaccinated, 5 cases received 1-dose and 36 cases received 2-dose vaccination. Among the 36 children who received 2 doses of vaccination, the time of viral nucleic acid negative conversion was shorter in those vaccinated within 6 months than those over 6 months ((7.1±1.9) vs. (10.8±3.0) d, t=-3.23, P=0.004). Univariate analysis showed that the time of nucleic acid negative conversion of SARS-CoV-2 was associated with age, underlying diseases, gastrointestinal symptoms, white blood cell count, proportion of neutrophils, proportion of lymphocytes, and the number of doses of SARS-CoV-2 vaccine (t=3.87, 2.55, 2.04, 4.24, 3.51, 2.92, F=16.27, all P<0.05). Multiple linear regression analysis showed that older age (β=-0.33, 95% CI -0.485--0.182, P<0.001) and more doses of vaccination (β=-0.79, 95% CI -1.463--0.120, P=0.021) were associated with shortened nucleic acid negative conversion time in children, while lower lymphocyte proportion (β=-0.02, 95% CI -0.044--0.002, P=0.031) and underlying diseases (β=1.52, 95% CI 0.363-2.672, P=0.010) were associated with prolonged nucleic acid negative conversion time in children. Conclusion: The children infected with Omicron variant of SARS-CoV-2 with reduced lymphocyte proportion and underlying diseases may have longer time of viral nucleic acid negative conversion,while children with older age and more doses of vaccination may have shorter time of viral nucleic acid negative conversion.
目的： 了解上海新型冠状病毒Omicron变异株感染患儿鼻咽拭子新型冠状病毒核酸转阴特点及其影响因素。 方法： 回顾性分析收集2022年4月25日至6月8日于上海交通大学医学院附属儿童医院（上海市新型冠状病毒感染患儿定点救治医院）因确诊新型冠状病毒感染住院的177例患儿的临床症状、实验室检查等资料。根据患儿胸部影像学表现分为轻型、普通型组；按感染年龄将未接种疫苗患儿分为<3岁、3~<18岁组；根据疫苗接种情况将3~<18岁患儿分为未接种、接种1剂次、接种2剂次组。组间比较采用独立样本t检验、方差分析，多因素分析采用多元线性回归分析。 结果： 177例新型冠状病毒Omicron变异株感染患儿中男96例、女81例，发病年龄3（1，6）岁，病毒核酸转阴时间为（10.3±3.1）d。轻型138例、普通型39例。3~<18岁新型冠状病毒疫苗接种适龄儿童中未接种疫苗55例、接种1剂次5例、接种2剂次36例。接种2剂次疫苗患儿末次疫苗接种时间≤6个月比>6个月病毒核酸转阴时间更短［（7.1±1.9）比（10.8±3.0）d，t=-3.23，P=0.004］。单因素分析显示新型冠状病毒核酸转阴时间受未接种疫苗患儿年龄、基础疾病、消化道症状、白细胞计数、中性粒细胞比例、淋巴细胞比例、新型冠状病毒疫苗接种情况的影响（t=3.87、2.55、2.04、4.24、3.51、2.92，F=16.27，均P<0.05）；多元线性回归分析显示年龄增长（β=-0.33，95%CI -0.485~-0.182，P<0.001）、接种新型冠状病毒灭活疫苗剂次增多（β=-0.79，95%CI -1.463~-0.120，P=0.021）是患儿病毒核酸转阴时间缩短的保护因素，淋巴细胞比例减少（β=-0.02，95%CI -0.044~-0.002，P=0.031）、有基础疾病（β=1.52，95%CI 0.363~2.672，P=0.010）则是患儿病毒核酸转阴时间延长的危险因素。 结论： 淋巴细胞比例减少、有基础疾病的新型冠状病毒Omicron变异株感染患儿病毒核酸转阴时间长，年龄增长、接种新型冠状病毒灭活疫苗剂次增多患儿病毒核酸转阴时间短。.