Table 1.

Ethical framework for CT apps: substantive and procedural values

Substantive values	Guiding questions
Public health benefit	Is the pandemic situation such that contact tracing activity is motivated from a public health standpoint? Is the general use of the CT app likely to enhance the effectiveness of contact tracing measures? Is the technological make-up of the app such that it can actually produce public health benefit? Is the pool of potential users who are willing to use a CT app large enough for epidemiological effectiveness?
Harm minimisation	Are CT apps the least harmful way of obtaining the desired benefits? Are CT apps easy to use and do they minimise confusion or stress by design? Has the risk of self- and social stigma effects, implicated by an elevated focus on one’s or others’ health status been considered and mitigated? Are safeguards in place to mitigate the vulnerability of and harm to marginalized groups from CT apps and related public health and security measures? Are potential, harmful social effects related to the app (widespread anxiety, ineffective quarantines etc.) adequately considered?
Privacy	Are measures in place for data protection and against data loss or misuse?Are data security authorities involved? Is data parsimony guaranteed and access to non-essential personal data minimised? Are the most privacy-preserving solutions (e.g. no real-time data, anonymization) prioritised? Is collection of the tracing-data temporary (e.g. will it be deleted after a certain, specified amount of time)? Is data sharing for other purposes excluded? Are appropriate cyber-resilience measures in place?
Justice	Has accessibility and availability been maximised Are benefits and burdens of CT apps equally distributed among the population? Will discrimination of vulnerable and structurally disadvantaged population groups be prevente? Are there measures to safely include marginalized groups or ‘digital immigrants’, without exacerbating their vulnerability? Will resulting scientific knowledge and insights be freely shared for the public good? Are different levels of digital literacy considered in app design?
Liberty/autonomy	Are users informed about possible consequences of CT app use? Are CT apps used voluntarily? Is there proper user consent for data use? Are users able to withdraw consent? Are there measures to avoid de-facto mandatory use, e.g. by restricting access to public or work space with CT apps? Are CT apps the least liberty-compromising measures compared to alternative strategies to pandemic management? Are there alternatives for those who choose not to participate in CT apps?
Solidarity	Are there measures to avoid negative effects on solidarity, e.g. by not imposing overly disproportionate burdens on specific groups? Has consideration been given to whether negative attitudes towards people who do not use the app may feed into practices of victim blaming?
Stewardship	Are effects of CT apps on existing infrastructure considered (e.g. encourage or strengthen power asymmetries, or market monopolies)? Are safeguards against function creep, i.e. the use beyond the purpose of the technology, in place? Are there strategies against malicious, fake CT apps? Are measures and policies reversible? Are CT apps embedded in robust regulatory frameworks? Are safeguards and oversight mechanisms in place? Are strategies in place to limit duration and end measures (sunset provisions)?

Procedural values	Guiding questions
Transparency	Are technological solutions and frameworks sufficiently transparent (e.g. open source)? Are purposes, objectives, as well as limitations of CT apps and measures clearly named and communicated? Are actors and possible stakes behind the CT apps transparent? Can CT apps be subject to an audit?
Proportionality	Are social, and moral costs of CT apps proportionate to the pandemic threat and the expected effectiveness of using the app? Is the cost-effectiveness of the CT app positive compared to alternative pandemic management strategies? Are financial costs proportionate to the expected public health benefits?
General trustworthiness	Are democratic procedures in place to guide decision making? Can population uptake be assumed? Do stated objectives of CT apps align with proposed measures?
Reasonableness	Is the proposed solution epidemiologically sound? Are the underlying considerations and models scientifically valid? Is there sufficient evidence that the CT app meets technical standards of reliance? Is the pandemic situation of a stage that makes contact tracing a priority from a public health standpoint? Is the app embedded in and of added value to a robust public health strategy with sufficient resources to test, trace and treat?
Accountability	Is it clear who can be held to account in the case of adverse outcomes, such as harm, infringements of rights or lack of effectiveness? Is there oversight of CT apps by legitimate governmental agencies and independent oversight bodies?
Consistency	Are CT measures and policies based on the same legal and ethical standards as other accepted measures of pandemic management? Are policies consistent with legal frameworks? Do strategies fit with local or national demands for pandemic management?
Engagement	Are there possibilities for the broader public to participate in decision making? Has input from relevant stakeholders (e.g. public authorities, health departments) been considered?
Reflexivity	Are there alternative strategies of contract tracing prepared if CT apps turn out to be inefficient and are there strategies in place to reverse decisions? Have the potential effects of CT apps on data monopolies be considered in decision making Are there research initiatives in place to evaluate the efficiency of CT apps?