Table 2.

Mapping of topics to normalization process theory constructs.

Normalization process theory construct			Topic domains (cf Table 1)		Assessment
Coherence (making sense of the intervention, ie, meaning and sense-making by participants)
	Is the intervention easy to describe?	D1, D2, E3, E6		DPTa is difficult to explain; some misconceptions of what DPT should achieve (eg, generating helpful data) or requirements for success (eg, need of 60% participation rate in population to be successful).
	Is it clearly distinct from other interventions?	C2		Because DPT is an adjunct to manual contact tracing, the distinction is not always obvious to all participants; DPT may even be seen as competition to manual tracing.
	Does it have a clear purpose for all relevant participants?	C2, D2		There were doubts about the purpose of DPT or even the right to coexist with manual contact tracing.
	Do participants have a shared sense of its purpose?	C2, D2		Not all participants are convinced, including parts of the population and cantonal health authorities.
	What benefits will the intervention bring and to whom?	C1, D1, D2, E6		Benefits are abstract, not immediately visible, and partially context dependent (eg, role of second line of defense).
	Are these benefits likely to be valued by potential participants?	D1, D2, E2, E4, E6		The overall potential benefits (slowing transmission) are valued by most, but doubts persist whether DPT can contribute toward that goal.
	Will it fit with the overall goals and activity of [pandemic mitigation goals]b?	N/Ac		DPT was designed to complement manual contact tracing; In principle, DPT is well aligned with other pandemic mitigation goals.
Cognitive participation (working out participation in the intervention, ie, commitment and engagement of participants)
	Are target user groups likely to think it is a good idea?	C1, C2, D1, D2		Some doubts seem to persist among all participants. Not all actors seem convinced of the benefits.
	Will they see the point of the intervention easily?	E3		DPT was released during a time when case numbers were low. Benefits remained abstract and unclear, in part also because of low infection numbers. Initially, this may have affected the willingness to engage in DPT work processes.
	Will they be prepared to invest time, energy, and work in it?	C1, C2		DPT was seen as competing for time and resources with other mitigation measures by some actors. Therefore, the willingness to engage in cognitive participation may have been limited.
Collective action (executing the intervention, ie, the work participants do to make the intervention function)
	How will the intervention affect the work of [participants]?	B1, B2, B3, B4, B5		DPT introduces additional steps and processes for MCTd. There were also some unclarities and frictions between different processes and interfaces (eg, between testing labs and cantonal physicians or between users with positive PCRe tests and cantonal physicians).
	Will it promote or impede their work?	B2, B5, C1, C2		DPT potentially adds to the workload of MCT; app use can be problematic for health care workers.
	What effect will it have on [interactions]?	B2, B3, B4, C2		DPT notifications are an additional dimension to be covered in MCT interviews; interface between infoline and cantonal health authorities needed optimization.
	Will staff require extensive training before they can use it?	A3, B4		In principle, yes, some reports indicate an additional need for instructions or communication for some (health system) actors.
	How compatible is it with existing work practices?	C2, D2, E5, E6		DPT is seen as something separate that adds to the workload. Data protection apparently inhibits complete DPT integration into MCT. Notified users may take actions, but not always as recommended (eg, directly seeking tests).
	What impact will it have on division of labor, resources, power, and responsibility between different professional groups?	B2, D2		Reports indicate several “interfacing” challenges, such as between infoline and cantonal health authorities. Reports of confusion regarding eligibility of free PCR testing for notified users.
Reflexive monitoring (reflecting on the intervention, ie, participants reflect on or appraise the intervention)
	How are users likely to perceive the intervention once it has been in use for a while?	D1, D2		Effectiveness still seems unclear or unproven for some actors. New case numbers of SARS-CoV-2 remained relatively low for most of the observation period, thus affecting perceived effectiveness.
	Is it likely to be perceived as advantageous for [users and other participants]?	C2, D1, D2		This seems not to be the case for all actors.
	Will it be clear what effects the intervention has had?	D1, D2		The uncertainty regarding DPT effectiveness hampers usage and implementation.
	Can users/participants contribute feedback about the intervention once it is in use?	N/A, but indicated by some reports.		App users gave indirect feedback (eg, via social media). Other actors had direct interactions with the Federal Office of Public Health and the app developers.
	Can the intervention be adapted or improved on the basis of experience?	N/A, but indicated by some reports.		App development is continuous; there is regular exchange about possible improvements.

^aDPT: digital proximity tracing.

^bExpressions in brackets reflect adaptations of the original question wordings [39] to better fit the current analysis.

^cN/A: not applicable.

^dMCT: manual contact tracing.

^ePCR: polymerase chain reaction.