Kremer Cécile, Willem Lander, Boone Jorden, Arrazola de Oñate Wouter, Hammami Naïma, Faes Christel, Hens Niel
Interuniversity Institute for Biostatistics and statistical Bioinformatics, Data Science Institute, Hasselt University, Hasselt, Belgium.
Centre for Health Economics Research and Modelling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.
PLoS One. 2023 Oct 20;18(10):e0292346. doi: 10.1371/journal.pone.0292346. eCollection 2023.
The goal of tracing, testing, and quarantining contacts of infected individuals is to contain the spread of infectious diseases, a strategy widely used during the COVID-19 pandemic. However, limited research exists on the effectiveness of contact tracing, especially with regard to key performance indicators (KPIs), such as the proportion of cases arising from previously identified contacts. In our study, we analyzed contact tracing data from Belgium collected between September 2020 and December 2021 to assess the impact of contact tracing on SARS-CoV-2 transmission and understand its characteristics. Among confirmed cases involved in contact tracing in the Flemish and Brussels-Capital regions, 19.1% were previously identified as close contacts and were aware of prior exposure. These cases, referred to as 'known' to contact tracing operators, reported on average fewer close contacts compared to newly identified individuals (0.80 versus 1.05), resulting in fewer secondary cases (0.23 versus 0.28). Additionally, we calculated the secondary attack rate, representing infections per contact, which was on average lower for the 'known' cases (0.22 versus 0.25) between December 2020 and August 2021. These findings indicate the effectiveness of contact tracing in Belgium in reducing SARS-CoV-2 transmission. Although we were unable to quantify the exact number of prevented cases, our findings emphasize the importance of contact tracing as a public health measure. In addition, contact tracing data provide indications of potential shifts in transmission patterns among different age groups associated with emerging variants of concern and increasing vaccination rates.
追踪、检测和隔离感染者的接触者，目的是遏制传染病传播，这是新冠疫情期间广泛采用的一项策略。然而，关于接触者追踪有效性的研究有限，尤其是在关键绩效指标（KPI）方面，比如由先前确定的接触者引发的病例比例。在我们的研究中，我们分析了2020年9月至2021年12月期间从比利时收集的接触者追踪数据，以评估接触者追踪对新冠病毒传播的影响并了解其特征。在弗拉芒大区和布鲁塞尔首都大区参与接触者追踪的确诊病例中，19.1%此前被确定为密切接触者且知晓此前接触情况。这些病例，被接触者追踪工作人员称为“已知”病例，与新确定的个体相比，平均报告的密切接触者较少（分别为0.80人和1.05人），导致的二代病例也较少（分别为0.23人和0.28人）。此外，我们计算了二代发病率，即每次接触导致的感染数，在2020年12月至2021年8月期间，“已知”病例的二代发病率平均较低（分别为0.22和0.25）。这些发现表明比利时的接触者追踪在减少新冠病毒传播方面是有效的。尽管我们无法量化确切预防的病例数，但我们的发现强调了接触者追踪作为一项公共卫生措施的重要性。此外，接触者追踪数据显示，随着关注的新变种出现和疫苗接种率上升，不同年龄组之间的传播模式可能发生变化。
