Corona is highly infectious, and this when the infected person is without symptoms, and may not show symptoms at all. The result is an exponential distribution of the virus unless measures such as social distances and wearing masks reduce the spreading. Once the number of new infections has come down, containment measures should prevent it from going up repeatedly.
Virologists speak of ‘stamping out’ infection chains, which requires testing as many people as feasible, quarantine each infected person, and find out with whom this person has been in near-enough contact for virus transmission, then test these persons, and so on. This track and tracing tasks is current practice in epidemics and traditionally carried out by health personnel or individuals, hired and trained for this task. This is where the contact tracing app comes in. With many people owning a smart phone, the idea is to use this device to spot with whom an infected person has been in contact during the incubation period. The expectation is to enhance the speed of contact tracing and improve coverage.
One approach is to use mobile connectivity data provided by operators to find out previous locations of people. People need not download an app. One disadvantage is that it is not precise enough for contact tracing. These data, however, support epidemiologists in following and analysing the geographical spread of the virus. The German Health Ministry, for instance, initially envisaged this approach but then shelved it because of privacy concerns.
Most countries have opted to operate an app, whereby Bluetooth data are preferred over GPS data as they are more precise and privacy-friendlier (no geo-location data). Google and Apple issued an architecture and an API to secure communication between iOS and Android phones. In doing so, they also introduced privacy settings that de facto limit the choice of national health authorities how to handle virus tracing. This is a good reminder for Europe’s digital sovereignty aspirations. https://www.blog.google/inside-google/company-announcements/apple-google-exposure-notification-api-launches/
Proximity measured by Bluetooth connectivity is not perfect. People can be close to each other but separated by a wall; they can be relatively distant but in a room with poor air circulation. Thus, the app is not the ultimate solution. Yet, it is the best solution we have to speed up virus exposure detection and save lives provided they are part of a ‘smart social distancing’ strategy. Without extensive testing, for instance, too many infected people will go unnoticed and with no timely information the app warnings will be insufficient. Also, sufficient people—experts say about 60% - must use the app to ensure coverage.
The coverage issue led to the question of voluntary or mandatory use of the app. If mandatory, then how can authorities enforce this obligation? So far only a few countries request the use of the app as an obligation. If voluntary, then how to persuade people to download and run the app? Strong privacy settings play a role.
Privacy concerns have dominated the debate about the contact tracing app. A core element was decentralised versus centralised storage of (encrypted) data. Who notifies people that they may have been exposed? In most of the apps design the infected person must trigger the warning, which puts a public health decision into the hands of private individuals. This is a win for the privacy advocates who have been very vocal in the debate. It is a testimony of our liberal society on the one hand and the rule of doctrines over pragmatic solutions on the other hand. Make your own judgement.
We discussed these issues around the Covid-19 contact tracing app in a webinar organised by FIPRA International. Read the full text on Fipra.com: