Li Jing, Li Jingjing, Dai Shuzhi, Dang Li, Wang Lin, Cao Ling, Chen Xiaobo, Wang Ying, Ge Menglei, Liu Weijie, Song Qinwei, Xu Wenjian, Ma Lijuan
Department of Clinical Laboratory, Children's Hospital, Capital Institute of Pediatrics, Beijing, China.
Department of Outpatient Treatment Center, Children's Hospital, Capital Institute of Pediatrics, Beijing, China.
Front Immunol. 2023 Sep 27;14:1269665. doi: 10.3389/fimmu.2023.1269665. eCollection 2023.
Analysis of SARS-CoV-2 IgG antibody and neutralizing antibody levels following SARS-CoV-2 infection in children aged 3-11 years, comparing those who had received the inactivated SARS-CoV-2 vaccine to those who were unvaccinated prior to infection, provides evidence for public health centers in formulating vaccination strategies and control policies.
A study was conducted on children who visited the Children's Hospital, Capital Institute of Pediatrics from January 10, 2023 to March 31, 2023 (Beijing, China). Participants or their guardians completed a survey questionnaire providing information about their SARS-CoV-2 infection history and vaccination status. Serum samples were collected for testing of SARS-CoV-2 immunoglobulin G (IgG) and neutralizing antibodies (Nabs), which were performed using chemiluminescence immunoassay.
The study included 1,504 children aged 3-11 years with previous SARS-CoV-2 infection history. Among the 333 unvaccinated children, the serum SARS-CoV-2 IgG antibody level was median 2.30 (IQR, 1.27-3.99). However, children received one dose (78 cases) and two doses (1093 cases) of the inactivated vaccine prior to infection showed significantly higher SARS-CoV-2 IgG antibody levels, with values of median 10.11 (IQR, 8.66-10.93) and median 10.58 (IQR, 9.79-11.07), respectively. As to the unvaccinated children, 70.3% (234/333) were negative for SARS-CoV-2 Nabs, which were less than 6.00AU/ml. The remaining 29.7% (99/333) showed relatively low levels of Nabs, ranging from 6.00 to 50.00AU/ml. In contrast, for children who had received two doses of vaccine prior to infection, an overwhelming 99.3% (1086/1093) exhibited high levels of Nas in the range of 100.00-120.00 AU/ml. Remarkably, these elevated Nab levels persisted for at least a period of 3 months post-infection in children who had received two doses of inactivated SARS-CoV-2 vaccine prior to infection, regardless of age or sex and vaccine manufacturer.
The administration of two doses of inactivated SARS-CoV-2 vaccine prior to infection has been shown to significantly enhance humoral immunity following SARS-CoV-2 infection in pediatric populations, producing adequate Nabs that persist at elevated levels for up to 3 months post-infection. For unvaccinated children who displayed weak humoral immunity following a primary natural infection, timely vaccination is recommended to bolster their immunization protection. The findings underscore the importance of vaccination in strengthening immune responses and protecting pediatric populations against SARS-CoV-2 infection.
分析3至11岁儿童感染新型冠状病毒2型（SARS-CoV-2）后的IgG抗体和中和抗体水平，比较感染前接种过SARS-CoV-2灭活疫苗的儿童与未接种疫苗的儿童，为公共卫生中心制定疫苗接种策略和防控政策提供依据。
对2023年1月10日至2023年3月31日期间前往首都儿科研究所附属儿童医院（中国北京）就诊的儿童进行了一项研究。参与者或其监护人完成了一份调查问卷，提供了他们的SARS-CoV-2感染史和疫苗接种状况信息。采集血清样本检测SARS-CoV-2免疫球蛋白G（IgG）和中和抗体（Nabs），检测采用化学发光免疫分析法。
该研究纳入了1504名有SARS-CoV-2既往感染史的3至11岁儿童。在333名未接种疫苗的儿童中，血清SARS-CoV-2 IgG抗体水平中位数为2.30（四分位间距，1.27 - 3.99）。然而，在感染前接种过一剂（78例）和两剂（1093例）灭活疫苗的儿童中，SARS-CoV-2 IgG抗体水平显著更高，中位数分别为10.11（四分位间距，8.66 - 10.93）和10.58（四分位间距，9.79 - 11.07）。对于未接种疫苗的儿童，70.3%（234/333）的SARS-CoV-2 Nabs呈阴性，低于6.00AU/ml。其余29.7%（99/333）的Nabs水平相对较低，范围为6.00至50.00AU/ml。相比之下，对于在感染前接种过两剂疫苗的儿童，绝大多数99.3%（1086/1093）的Nabs水平较高，在100.00 - 120.00 AU/ml范围内。值得注意的是，对于在感染前接种过两剂SARS-CoV-2灭活疫苗的儿童，无论年龄、性别和疫苗生产商如何，这些升高的Nab水平在感染后至少持续3个月。
已表明在感染前接种两剂SARS-CoV-2灭活疫苗可显著增强儿童人群感染SARS-CoV-2后的体液免疫，产生足够的Nabs，且在感染后高水平持续长达3个月。对于初次自然感染后体液免疫较弱的未接种疫苗儿童，建议及时接种疫苗以增强免疫保护。研究结果强调了接种疫苗在加强免疫反应和保护儿童人群免受SARS-CoV-2感染方面的重要性。
