学术观点｜面对疫情，校园的开放与关闭
教育环境中的感染几率较低研究发现，总体而言，与社区和家庭相比，儿童和青少年在教育环境中感染的几率较低。虽然儿童和青少年感染新冠的相关证据也在不断演变当中，但研究也指出，扩大儿童和青少年的疫苗接种可能是让儿童重返学校的最有效策略。
图源｜新华社
作者介绍
Omar Irfan, 多伦多大学全球儿童健康研究中心
蒋励，多伦多大学全球儿童健康研究中心，研究员
唐昆，清华大学万科公共卫生与健康学院，副教授
王志成，清华大学万科公共卫生与健康学院，博士
Zulfiqar A Bhutta ，巴基斯坦阿迦汗大学，全球健康与发展研究所
导读
近两周疫情的反复再次引发公众关注，开学在即，校园防控政策尤其是校园是否会再次关闭，成为社会讨论的焦点之一。7月31日，北京众多中小学家长接到通知，按照防控防疫最新要求，为了做好秋季开学准备，出京师生，需距离开学14天（8月15日）之前返京，并且按照卫生防疫要求，做好健康监测工作。随着各类病毒变种出现，政策调整所依赖的社会环境和科学依据也变得更为复杂，而解答上述焦点问题的前提，是评估教育环境中存在的感染和传播风险。
实际上，随着新型冠状病毒肺炎（COVID-19）在全球蔓延，如何在这场全球大流行中保证儿童和青少年人群的健康一直是学术界关注的重点。2020年以来，许多研究针对儿童和青少年感染和传播新冠的风险进行了调查。2021年7月，清华大学万科公共卫生与健康学院唐昆团队与多伦多大学全球儿童健康研究中心（Centre for Global Child Health）在《全球卫生杂志》（Journal of Global Health）合作发表了题为“家庭、社区和教育环境中儿童和青少年SARS-CoV-2的感染和传播风险：系统综述和Meta分析”（Risk of infection and transmission of SARS-CoV-2 among children and adolescents in households, communities and educational settings: A systematic review and meta-analysis）的研究综述及分析。
文章主要目标在于调查儿童和青少年感染和传播新冠的风险，以及该人群在不同环境中对新冠传播所起到的作用。文章回顾了截止2021年4月1日全球已发表的来自31个不同国家的90项研究，检索了PubMed, EMBASW, Cochrane Library, WHO COVID-19 Database等数据库中的国家和次国家流行率研究，以及家庭、社区和教育环境中的接触者追踪研究（CTS）。
教育环境中的感染几率较低
研究发现，总体而言，与社区和家庭相比，儿童和青少年在教育环境中感染的几率较低。相比之前的文献更多在新冠大流行的早期阶段进行，这项研究提供了更新更全面的数据。这些数据表明，尽管儿童一直被认为是流感和麻疹的“超级传播者”，但儿童并不像成人那样容易感染新冠，并且在各种情况下，儿童对于新冠传播所起的作用都十分有限。
家庭感染风险是学校的2倍多，教育中断带来更多问题
同时，研究还发现，开放学校可能并不会使儿童和青少年更容易感染新冠，相反，儿童和青少年在家庭和社区环境中感染的风险是学校的2倍多。而另一方面，有研究表明，长期关闭学校，对儿童、青少年的教育和发展都将带来负面影响，包括精神障碍、营养恶化、体育活动缺乏以及家庭暴力虐待等。教育中断对正处于学习敏感期的儿童影响最为明显，可能会永久性地影响一个人的基础技能发展。虽然儿童和青少年感染新冠的相关证据也在不断演变当中，但研究也指出，扩大儿童和青少年的疫苗接种可能是让儿童重返学校的最有效策略。
文章摘要
01
Background
There is uncertainty with respect to SARS-CoV-2 transmission in children (0-19 years) with controversy on effectiveness of school-closures in controlling the pandemic. It is of equal importance to evaluate the risk of transmission in children who are often asymptomatic or mildly symptomatic carriers that may incidentally transmit SARS-CoV-2 in different settings. We conducted this review to assess transmission and risks for SARS-CoV-2 in children (by age-groups or grades) in community and educational-settings compared to adults.
02
Methods
Data for the review were retrieved from PubMed, EMBASE, Cochrane Library, WHO COVID-19 Database, China National Knowledge Infrastructure (CNKI) Database, WanFang Database, Latin American and Caribbean Health Sciences Literature (LILACS), Google Scholar, and preprints from medRixv and bioRixv) covering a timeline from December 1, 2019 to April 1, 2021. Population-screening, contact-tracing and cohort studies reporting prevalence and transmission of SARS-CoV-2 in children were included. Data were extracted according to PRISMA guidelines. Meta-analyses were performed using Review Manager 5.3.
03
Results
Ninety studies were included. Compared to adults, children showed comparable national (risk ratio (RR) = 0.87, 95% confidence interval (CI) = 0.71-1.060 and subnational (RR = 0.81, 95% CI = 0.66-1.01) prevalence in population-screening studies, and lower odds of infection in community/household contact-tracing studies (odds ratio (OR) = 0.62, 95% CI = 0.46-0.84). On disaggregation, adolescents observed comparable risk (OR = 1.22, 95% CI = 0.74-2.04) with adults. In educational-settings, children attending daycare / preschools (OR = 0.53, 95% CI = 0.38-0.72) were observed to be at lower-risk when compared to adults, with odds of infection among primary (OR = 0.85, 95% CI = 0.55-1.31) and high-schoolers (OR = 1.30, 95% CI = 0.71-2.38) comparable to adults. Overall, children and adolescents had lower odds of infection in educational-settings compared to community and household clusters.
04
Conclusions
Children (<10 years) showed lower susceptibility to COVID-19 compared to adults, whereas adolescents in communities and high-schoolers had comparable risk. Risks of infection among children in educational-settings was lower than in communities. Evidence from school-based studies demonstrate it is largely safe for children (<10 years) to be at schools, however older children (10-19 years) might facilitate transmission. Despite this evidence, studies focusing on the effectiveness of mitigation measures in educational settings are urgently needed to support both public health and educational policy-making for school reopening.
END
图源 | 网络
编辑 | 张如东 王志成 吕心怡
美编 | 余珊珊
监制 | 唐昆
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