小柯机器人

瑞士日内瓦大学医院Silvia Stringhini团队对瑞士日内瓦抗SARS-CoV-2 IgG抗体的血清流行率进行了分析。2020年6月11日，《柳叶刀》杂志在线发表了这一成果。

鉴于COVID-19依赖于检测策略、不断变化的病例定义和疾病表现，因此，根据医疗参与病例数评估其负担并非最优。基于人群的血清学测试可检测抗SARS-CoV-2抗体，提供了一种估算感染率和监测流行病进展的方法。研究组估计了流行病期间瑞士日内瓦人口中抗SARS-CoV-2抗体的每周血清阳性率。

研究组计划对先前人口代表性调查中随机选择的参与者及其5岁及以上的家庭成员进行连续12次每周血清测试。研究组使用市售的ELISA检测了每个参与者的抗SARS-CoV-2-IgG抗体，使用贝叶斯逻辑回归模型估算血清阳性率，并根据日内瓦人口的年龄和性别进行了校正。

2020年4月6日至5月9日，研究组招募了来自1339个家庭的2766名参与者，其人口分布与日内瓦相似。第一周，研究组估计血清阳性率为4.8%，第二周增加到8.5%，第三周增加到10.9%，第四周为6.6%，第五周为10.8%。5-9岁和65岁以上的参与者与20-49岁的人群相比，血清阳性风险显著降低。在考虑了血清转化时间之后，研究组估计每报告1例确诊病例，社区中就有11.6例感染者。

虽然日内瓦COVID-19患病率很高，但在这一波大流行中，日内瓦大多数人口仍未受到感染。假设IgG抗体的存在与免疫力有关，这些结果表明，该流行病还远没有通过人口中较少的易感人群而终结。且与10-64岁相比，5-9岁儿童和65岁以上老年人的血清阳性率显著降低。

附：英文原文

Title: Seroprevalence of anti-SARS-CoV-2 IgG antibodies in Geneva, Switzerland (SEROCoV-POP): a population-based study

Author: Silvia Stringhini, Ania Wisniak, Giovanni Piumatti, Andrew S Azman, Stephen A Lauer, Hélène Baysson, David De Ridder, Dusan Petrovic, Stephanie Schrempft, Kailing Marcus, Sabine Yerly, Isabelle Arm Vernez, Olivia Keiser, Samia Hurst, Klara M Posfay-Barbe, Didier Trono, Didier Pittet, Laurent Gétaz, Franois Chappuis, Isabella Eckerle, Nicolas Vuilleumier, Benjamin Meyer, Antoine Flahault, Laurent Kaiser, Idris Guessous

Issue&Volume: 2020-06-11

Abstract: Background

Assessing the burden of COVID-19 on the basis of medically attended case numbers is suboptimal given its reliance on testing strategy, changing case definitions, and disease presentation. Population-based serosurveys measuring anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) antibodies provide one method for estimating infection rates and monitoring the progression of the epidemic. Here, we estimate weekly seroprevalence of anti-SARS-CoV-2 antibodies in the population of Geneva, Switzerland, during the epidemic.

Methods

The SEROCoV-POP study is a population-based study of former participants of the Bus Santé study and their household members. We planned a series of 12 consecutive weekly serosurveys among randomly selected participants from a previous population-representative survey, and their household members aged 5 years and older. We tested each participant for anti-SARS-CoV-2-IgG antibodies using a commercially available ELISA. We estimated seroprevalence using a Bayesian logistic regression model taking into account test performance and adjusting for the age and sex of Geneva's population. Here we present results from the first 5 weeks of the study.

Findings

Between April 6 and May 9, 2020, we enrolled 2766 participants from 1339 households, with a demographic distribution similar to that of the canton of Geneva. In the first week, we estimated a seroprevalence of 4·8% (95% CI 2·4–8·0, n=341). The estimate increased to 8·5% (5·9–11·4, n=469) in the second week, to 10·9% (7·9–14·4, n=577) in the third week, 6·6% (4·3–9·4, n=604) in the fourth week, and 10·8% (8·2–13·9, n=775) in the fifth week. Individuals aged 5–9 years (relative risk [RR] 0·32 [95% CI 0·11–0·63]) and those older than 65 years (RR 0·50 [0·28–0·78]) had a significantly lower risk of being seropositive than those aged 20–49 years. After accounting for the time to seroconversion, we estimated that for every reported confirmed case, there were 11·6 infections in the community.

Interpretation

These results suggest that most of the population of Geneva remained uninfected during this wave of the pandemic, despite the high prevalence of COVID-19 in the region (5000 reported clinical cases over <2·5 months in the population of half a million people). Assuming that the presence of IgG antibodies is associated with immunity, these results highlight that the epidemic is far from coming to an end by means of fewer susceptible people in the population. Further, a significantly lower seroprevalence was observed for children aged 5–9 years and adults older than 65 years, compared with those aged 10–64 years. These results will inform countries considering the easing of restrictions aimed at curbing transmission.

DOI: 10.1016/S0140-6736(20)31304-0

Source: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31304-0/fulltext

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