gms | German Medical Science

Background and status of (inter)national research: Digital contact tracing can be an effective tool in helping to contain the COVID-19 pandemic. However, the number of Corona-Warn-App (CWA) downloads is still too low to noticeably relieve health authorities. Our study investigates how nudging could be a useful supplement to traditional advertising activities to increase app downloads. Thus, the study contributes to the growing literature on the promotion of the CWA, as one example for mobile health (mHealth) applications. It also provides insights on the acceptance of a default, respectively mandated choice, policy.

Question and objective: While there are objections to the mandatory use of digital contact tracing apps, the aim of this study is to analyze whether and how nudging – a means of influencing people towards a certain decision while preserving their freedom to choose – can support the adoption of the German CWA.

Method or hypothesis: The research focused on the effectiveness of social norm nudges and the acceptance of two hypothetical policies: one in which the CWA was installed and activated by default on participants' smartphones, and one in which the app was installed but participants had a choice on whether or not to activate the app (mandated choice policy). To answer the research question, we conducted two online-experiments.

Results: In contrast to our expectations, the social norm nudges did not appear to have a significant impact on the intention to adopt the CWA. However, participants not having already installed the app show at least a neutral attitude towards a mandated choice setting for the app installation.

Discussion: We did not find a significant influence of a social norm message on the intention to adopt the CWA. Thus, for the CWA a social norm nudge might not be effective. Recent studies support our findings that messages appealing to the community spirit do not have a significant impact on the installation of the CWA1. The ceiling effect might explain why the social norm nudges had no effect, but also the fact that app non-users may already have had a too entrenched opinion of the CWA could be a reason [1]. Changing the status quo of app installation is likely to have a significantly higher impact on the usage rate. Among respondents who had not yet installed the app, the actual target group of the policies, a majority was not in favor of a default regulation. In contrast, the mean acceptance of a mandated choice policy was nearly neutral among this group. For both hypothetical policies, though, the expected performance of the CWA and the prospective impact of the policy on the number of active users had a significant impact on the acceptance. Thus, communicating the effectiveness of such opt-out policies can help drive their acceptance, which could also improve the app's perceived value.

Practical implications: Based on our results, we suggest implementing a mandated choice policy, combined with information about the performance and potential impact of the CWA.

Appeal for practice: Nudging is a promising approach to increase the usage rate of mHealth applications.