小柯机器人

瑞士苏黎世大学Susi Kriemler团队研究了苏黎世州学龄儿童SARS-CoV-2血清流行率的聚集性和纵向变化。2020年3月17日，《英国医学杂志》发表了该成果。

为了研究SARS-CoV-2血清流行率的纵向变化，并确定2020年6月至11月瑞士苏黎世州学校班级血清阳性儿童的聚集情况，研究组设计了一项前瞻性队列研究。

瑞士是2020年秋季欧洲SARS-CoV-2大流行第二波疫情最严重的国家之一。保持学校开放为研究SARS-CoV-2感染提供了一个中高度的暴露环境。研究组随机抽取学校和班级的儿童，按地区分层，进行SARS-CoV-2血清学检测，他们的父母完成了关于社会人口和健康相关问题的问卷调查。

参与者年龄范围为6-16岁，来自55所学校的275个班级。2020年6月至7月有2603名儿童参加，2020年10月至11月有2552名儿童参加。主要观察指标为：2020年6-7月和10-11月SARS-CoV-2血清学、班级内血清阳性儿童的聚集情况以及儿童的症状。

2020年6～7月，2496例儿童中有74例血清阳性；10～11月，2503例儿童中有173例血清阳性。在此前血清阴性的儿童中，SARS-CoV-2血清总流行率在夏季为2.4%，在深秋为4.5%，因此约有7.8%的儿童血清呈阳性。不同地区的血清流行率不同（秋季为1.7%至15.0%不等）。低、中、高年级儿童（分别为6-9岁、9-13岁和12-16岁）之间无显著差异。

2223名儿童在两轮检测中都进行了血清学检查，其中先前血清阳性者中有40%转为血清阴性，先前血清阴性者中有5%转为血清阳性。自夏季以来，22%的血清阴性儿童和29%的新发血清阳性儿童出现了症状。2020年7月至11月，确诊SARS-CoV-2感染的儿童与血清阳性儿童的比率为1：8。

在55所学校中的47所学校和275个班级中的90个班级中，至少发现了一名新发血清阳性儿童。在130个参与率高的班级中，73个班级（56%）未发现血清阳性儿童，50个班级（38%）有1至2名儿童血清阳性，7个班级（5%）至少有3名儿童血清阳性。在多水平logistic回归模型中，班级水平和学校水平分别解释了24%和8%的血清阳性差异。

总之，由于学校自2020年8月开放，并采取了一些预防措施，因此尽管在社区中SARS-CoV-2中高度传播期间，血清阳性儿童的总体血清流行率有所上升，但只有少数班级出现了聚集现象。

附：英文原文

Title: Clustering and longitudinal change in SARS-CoV-2 seroprevalence in school children in the canton of Zurich, Switzerland: prospective cohort study of 55 schools

Author: Agne Ulyte, Thomas Radtke, Irene A Abela, Sarah R Haile, Christoph Berger, Michael Huber, Merle Schanz, Magdalena Schwarzmueller, Alexandra Trkola, Jan Fehr, Milo A Puhan, Susi Kriemler

Issue&Volume: 2021/03/17

Abstract:

Objectives To examine longitudinal changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and to determine the clustering of children who were seropositive within school classes in the canton of Zurich, Switzerland from June to November 2020.

Design Prospective cohort study.

Setting Switzerland had one of the highest second waves of the SARS-CoV-2 pandemic in Europe in autumn 2020. Keeping schools open provided a moderate to high exposure environment to study SARS-CoV-2 infections. Children from randomly selected schools and classes, stratified by district, were invited for serological testing of SARS-CoV-2. Parents completed questionnaires on sociodemographic and health related questions.

Participants 275 classes in 55 schools; 2603 children participated in June-July 2020 and 2552 in October-November 2020 (age range 6-16 years).

Main outcome measures Serology of SARS-CoV-2 in June-July and October-November 2020, clustering of children who were seropositive within classes, and symptoms in children.

Results In June-July, 74 of 2496 children with serological results were seropositive; in October-November, the number had increased to 173 of 2503. Overall SARS-CoV-2 seroprevalence was 2.4% (95% credible interval 1.4% to 3.6%) in the summer and 4.5% (3.2% to 6.0%) in late autumn in children who were not previously seropositive, leading to an estimated 7.8% (6.2% to 9.5%) of children who were ever seropositive. Seroprevalence varied across districts (in the autumn, 1.7-15.0%). No significant differences were found among lower, middle, and upper school levels (children aged 6-9 years, 9-13 years, and 12-16 years, respectively). Among the 2223 children who had serology tests at both testing rounds, 28/70 (40%) who were previously seropositive became seronegative, and 109/2153 (5%) who were previously seronegative became seropositive. Symptoms were reported for 22% of children who were seronegative and 29% of children who were newly seropositive since the summer. Between July and November 2020, the ratio of children diagnosed with SARS-CoV-2 infection to those who were seropositive was 1 to 8. At least one child who was newly seropositive was detected in 47 of 55 schools and in 90 of 275 classes. Among 130 classes with a high participation rate, no children who were seropositive were found in 73 (56%) classes, one or two children were seropositive in 50 (38%) classes, and at least three children were seropositive in 7 (5%) classes. Class level explained 24% and school level 8% of variance in seropositivity in the multilevel logistic regression models.

Conclusions With schools open since August 2020 and some preventive measures in place, clustering of children who were seropositive occurred in only a few classes despite an increase in overall seroprevalence during a period of moderate to high transmission of SARS-CoV-2 in the community. Uncertainty remains as to whether these findings will change with the new variants of SARS-CoV-2 and dynamic levels of community transmission.

DOI: 10.1136/bmj.n616

Source: https://www.bmj.com/content/372/bmj.n616

BMJ-British Medical Journal:《英国医学杂志》，创刊于1840年。隶属于BMJ出版集团，最新IF：93.333
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