Epidemiology, Biostatistics and Prevention Institute, University of Zürich, Switzerland.
Department of Health Care Policy, Harvard Medical School, USA.
Swiss Med Wkly. 2022 Jun 13;152:w30193. doi: 10.4414/smw.2022.w30193. eCollection 2022 Jun 6.
Few studies have directly examined the incidence or seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in children, parents and teachers from the same school communities. This study aimed to describe SARS-CoV-2 seroprevalence within cantonal districts and school communities in children, parents and school personnel in June-September 2020 and March-April 2021 in the canton of Zürich, Switzerland.
We invited children from 55 randomly selected primary and secondary schools and 275 classes within them to participate in the Ciao Corona study in June-July 2020. Parents of the participating children and all school personnel were invited in August-September 2020. Eligible classes, parents and school personnel were tested again in March-April 2021. Venous blood was tested for SARS-CoV-2 serology. We collected sociodemographic information of the participants in online questionnaires on enrolment in the study. We excluded vaccinated adults and those with unverified vaccination status from the main analysis. Seroprevalence estimates were adjusted for test accuracy. We assessed the variability of seroprevalence within and across cantonal districts and school communities and compared it with the per capita cumulative incidence of confirmed SARS-CoV-2 infections.
In June-September 2020, 2,473 children, 1,608 school personnel and 2,045 parents participated in the study. In June-September 2020, seroprevalence was low (4.4% to 5.8%) in all cohorts. In March-April 2021, seroprevalence in children and parents (18.1% and 20.9%) was slightly higher than in school personnel (16.9%). We observed a large variation in seroprevalence estimates of the three cohorts within and between districts and school communities, with the median ratio of children's seroprevalence to per capita confirmed cases in district inhabitants of 3.1 (interquartile range 2.6 to 3.9). Seroprevalence was lower in children in the upper school level and their parents, but not teachers. Children's seroprevalence was slightly higher in classes with infected main teachers and families with one infected parent and substantially higher in families with two infected parents.
We observed similar seroprevalence in children and parents, somewhat lower in school personnel in March-April 2021 and striking variation between districts and school communities. Children's seroprevalence was higher in classes with infected main teachers and from families with infected parents.
鲜有研究直接调查过来自同一学校社区的儿童、家长和教师中严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染的发病率或血清流行率。本研究旨在描述 2020 年 6 月至 9 月和 2021 年 3 月至 4 月间瑞士苏黎世州各市区和学校社区内儿童、家长和学校人员的 SARS-CoV-2 血清阳性率。
我们邀请了来自 55 所随机选定的小学和中学以及其中 275 个班级的儿童参加 2020 年 6 月至 7 月的 Ciao Corona 研究。参与儿童的家长以及所有学校人员于 2020 年 8 月至 9 月受邀参加。有资格的班级、家长和学校人员于 2021 年 3 月至 4 月再次接受检测。采集静脉血检测 SARS-CoV-2 血清学。我们通过在线问卷调查收集了参与者的社会人口统计学信息。我们将主要分析中未接种疫苗的成年人和未核实疫苗接种状况的成年人排除在外。对血清阳性率估计值进行了检测准确性调整。我们评估了各市区和学校社区内和之间的血清阳性率变异性，并将其与经证实的 SARS-CoV-2 感染的人均累计发病率进行了比较。
2020 年 6 月至 9 月，2473 名儿童、1608 名学校人员和 2045 名家长参加了该研究。在所有队列中，2020 年 6 月至 9 月的血清阳性率均较低（4.4%至 5.8%）。2021 年 3 月至 4 月，儿童和家长的血清阳性率（18.1%和 20.9%）略高于学校人员（16.9%）。我们观察到各市区和学校社区内和之间三个队列的血清阳性率估计值存在较大差异，各市区居民中儿童血清阳性率与经证实的病例的中位数比值为 3.1（四分位间距 2.6 至 3.9）。高年级儿童及其家长的血清阳性率较低，但教师的血清阳性率没有差异。感染主要教师的班级以及有一名感染家长的家庭中儿童的血清阳性率略高，而有两名感染家长的家庭中儿童的血清阳性率显著更高。
我们观察到儿童和家长的血清阳性率相似，2021 年 3 月至 4 月时学校人员的血清阳性率略低，且各市区和学校社区之间存在显著差异。感染主要教师的班级以及有感染家长的家庭中儿童的血清阳性率更高。
