Department of Public Health, Institute of Tropical Medicine, 2000 Antwerp, Belgium.
Department of Laboratory Medicine, National Reference Centre for Respiratory Pathogens, University Hospitals Leuven, 3000 Leuven, Belgium.
Epidemics. 2022 Sep;40:100589. doi: 10.1016/j.epidem.2022.100589. Epub 2022 Jun 3.
To better understand the conditions which have led to one of the largest COVID-19 outbreaks in Belgian nursing homes in 2020.
A nursing home in Flanders, Belgium, which experienced a massive outbreak of COVID-19 after a cultural event. An external volunteer who dressed as a legendary figure visited consecutively the 4 living units on December, 4th and tested positive for SARS-CoV-2 the next day. Within days, residents started to display symptoms and the outbreak spread rapidly within the nursing home.
We interviewed key informants and collected standardized data from all residents retrospectively. A batch of 115 positive samples with a Ct value of < 37 by qRT-PCR were analyzed using whole-genome sequencing. Six months after the outbreak, ventilation assessment of gathering rooms in the nursing home was done using a tracer gas test with calibrated CO sensors.
Timeline of diagnoses and symptom onsets clearly pointed to the cultural event as the start of the outbreak, with the volunteer as index case. The genotyping of positive samples depicted the presence of one large cluster, suggesting a single source outbreak. By the end of December, a total of 127 residents and 40 staff were diagnosed with SARS-CoV-2 since the beginning of the outbreak. The attack rate among residents was 77 % and significantly associated with presence at the event but not with close contact or mask wearing. The ventilation assessment showed a high background average CO level in four main rooms varying from 657 ppm to 846 ppm.
Our investigation shows a rapid and widespread single source outbreak of SARS-CoV-2 in a nursing home, in which airborne transmission was the most plausible explanation for the massive intra-facility spread. Our results underscore the importance of ventilation and air quality for the prevention of future outbreaks in closed facilities.
更好地了解 2020 年比利时养老院发生的最大 COVID-19 疫情之一的相关情况。
比利时佛兰德的一家养老院在一场文化活动后发生了大规模的 COVID-19 疫情爆发。一名志愿者乔装成传奇人物，连续四天访问了 4 个居住单元，第二天检测出 SARS-CoV-2 呈阳性。几天之内，居民开始出现症状，疫情在养老院迅速蔓延。
我们采访了关键知情人，并从所有居民那里收集了回顾性的标准化数据。对一批 115 个 Ct 值<37 的阳性样本进行了 qRT-PCR 分析，并用全基因组测序进行了分析。疫情爆发六个月后，使用带有校准 CO 传感器的示踪气体测试对养老院的聚集室进行了通风评估。
诊断和症状发作的时间线清楚地表明，文化活动是疫情的开始，志愿者是该起疫情的源头。阳性样本的基因分型描绘了一个大集群的存在，表明是单一来源的爆发。截至 12 月底，自疫情爆发以来，共有 127 名居民和 40 名员工被诊断出患有 SARS-CoV-2。居民的发病率为 77%，与事件发生有显著相关性，但与密切接触或戴口罩无关。通风评估显示，四个主要房间的背景平均 CO 水平较高，范围从 657ppm 到 846ppm。
我们的调查显示，在一家养老院中，SARS-CoV-2 迅速而广泛地发生了单一来源的爆发，空气传播是设施内大规模传播的最可能解释。我们的研究结果强调了通风和空气质量对于预防未来在封闭设施中发生疫情的重要性。
