Since the start of the COVID-19 pandemic, technology enthusiasts have pushed for digital contact tracing as a critical tool for breaking the COVID-19 transmission chains. Motivated by this push, many countries and companies have created apps that enable digital contact tracing with the goal to identify the chain of transmission from an infected individual to others and enable early quarantine. Digital contact tracing applications like AarogyaSetu in India, TraceTogether in Singapore, SwissCovid in Switzerland, and others have been downloaded hundreds of millions of times. Yet, this technology hasn't seen the impact that we envisioned at the start of the pandemic. Some countries have rolled back their apps, while others have seen low adoption [12, 17]. Therefore, it is prudent to ask what the technology landscape of contact-tracing looks like and what are the missing pieces. We attempt to undertake this task in this paper. We present a high-level review of technologies underlying digital contact tracing, a set of metrics that are important while evaluating different contact tracing technologies, and evaluate where the different technologies stand today on this set of metrics. Our hope is two fold: (a) Future designers of contact tracing applications can use this review paper to understand the technology landscape, and (b) Researchers can identify and solve the missing pieces of this puzzle, so that we are ready to face the rest of the COVID-19 pandemic and any future pandemics. A majority of this discussion is focused on the ability to identify contact between individuals. The questions of ethics, privacy, and security of such contact tracing are briefly mentioned but not discussed in detail.

中文翻译：

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数字接触者追踪

自 COVID-19 大流行开始以来，技术爱好者一直在推动数字接触者追踪作为打破 COVID-19 传播链的关键工具。在这种推动下，许多国家和公司创建了应用程序来实现数字接触者追踪，目的是识别从受感染个体到其他人的传播链并实现早期隔离。印度的 AarogyaSetu、新加坡的 TraceTogether、瑞士的 SwissCovid 等数字联系人追踪应用程序已被下载数亿次。然而，这项技术还没有看到我们在大流行开始时所设想的影响。一些国家/地区已经回滚了他们的应用程序，而另一些国家/地区的采用率较低 [12, 17]。所以，谨慎的做法是询问接触者追踪的技术前景是什么样的，以及缺失的部分是什么。我们试图在本文中承担这项任务。我们对数字接触者追踪技术进行了高层次的回顾，这是一组在评估不同接触者追踪技术时很重要的指标，并评估了不同技术在这组指标上的地位。我们的希望有两个：（a）未来的接触者追踪应用程序设计者可以使用这篇评论文章来了解技术前景，（b）研究人员可以识别和解决这个难题的缺失部分，以便我们准备好面对其余的 COVID-19 大流行和任何未来的大流行。本次讨论的大部分内容都集中在识别个人之间联系的能力上。道德、隐私等问题