A Review of: ‘People Count: Contact-Tracing Apps and Public Health’

Cybersecurity expert Prof. Susan Landau’s valuable and insightful recent book, People Count: Contact-Tracing Apps and Public Health, stresses that trust in government is essential to making contact tracing work for everyone. 

Contact tracing is a process for identifying, informing, and monitoring people who might have come into contact with a person who has been diagnosed with an infectious disease such as COVID-19.  It starts with a positive test. Public health officials then need to know who that person might have inadvertently infected. This requires tracking down anyone that person had contacted (was “close enough” for “long enough”) recently (14 days in the case of COVID). They can then be informed that they might have been infected and take measures to quarantine and monitor for symptoms. For example, restaurants initiate tracing by recording the name and phone number of one person in each party taking a table in the restaurant. 

Contract tracing is vital in a pandemic, enabling warnings for people who have been close to someone who seems OK but later proves to have been infected. As Prof. Landau describes in detail, contact tracing has long been used for to limit the spread of infectious diseases such as smallpox, typhoid, HIV/AIDS, and Ebola. Because COVID can be spread by asymptomatic individuals, even those protected by vaccination, it is an essential tool in the public health arsenal. 

We can imagine digital contact tracing policies ranging from the laissez-faire to authoritarian, with the goal of saving lives. On the one hand, a government could do nothing. At the other extreme, a government could insert a smart chip into every citizen. The chip through communication with other chips would be able to report to the government with great accuracy every contact. If the chip were also capable of voice recognition, it might even be able to submit an Orwellian report if one person admitted to another that s/he was experiencing symptoms. 

Most societies have done something, although happily none have inserted chips. South Korea and Singapore instituted far-reaching contact tracing methodologies. South Korea used a combination of gathering and integrating credit card usage data, cell phone location logs, and surveillance camera footage. Nearly 80% of Singapore’s residents used their TraceTogether system, which tracked people using either a cell phone app or small physical tokens. Although contact tracing is only one part of effective infection control, the percentage of the population that have been infected in these countries is 7000 per million in South Korea and 36,000 per million in Singapore, compared to 142,000 per million in the U.S. (as of early November 2021). The Singapore data was reportedly shared with the police. Prof. Landau’s book reviews technologies that can contribute to contact tracing and how they were used in 2020 by other countries such as India. She also explains some of the subtleties in the synergistic use of digital data and human investigation for effective contact tracing. Use of a contact tracing app in the United Kingdom is estimated to have averted 600,000 possible infections in six months. 

Because of privacy concerns — possible exposure of sensitive private data about who you were with when and where, contact tracing approaches have typically been replaced by apps using the GAEN (Google-Apple Exposure Notification) software.Such software exemplifies a privacy-sensitive Value Sensitive Design methodology, in that it tracks only proximity and notifies users if they have been close to an infected person. Unlike Contact Tracing apps, Exposure Notification apps do not collect location information, nor do they send data to the government. GAEN systems protect privacy, yet they are not as effective as true contact tracing, especially in understanding and dealing with superspreader events.

Landau’s most interesting discussion is Chapter 5’s review of the many quantitative, physical, biological, psychological, pragmatic, cultural, and socio-economic influences on the effectiveness of digital contact tracing and exposure notification, and the obstacles in realizing an effective test–>trace–>isolate regimen. She discusses the tradeoff illustrated by contact tracing between public safety and personal privacy. Prof. Landau is especially passionate in discussing how a history of systemic racism leads to distrust of government by many racialized poor people and a reluctance to use its technology, no matter how noble the stated motives are.


What level of contact tracing, with what involvement by government, would you support and why? 

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