Predicting the use of a COVID-19 contact tracing application: A study across two points of measurements.

Contact tracing mobile applications (apps) were important in combating the COVID-19 pandemic. Most previous studies predicting contact tracing app use were cross-sectional and not theory-based. This study aimed at contributing to a better understanding of app use intentions and app use by applying an extended version of the protection motivation theory across two measurement points while accounting for the development of the pandemic. A total of N = 1525 participants from Switzerland (Mage = 53.70, SD = 18.73; 47% female; n = 270 completed both assessments) reported on risk perceptions, response efficacy, self-efficacy, social norms, trust in government, trust in the healthcare system, active search of COVID-19-related information, intentions for and actual (self-reported) app use. Analyses included country-specific incidences and death toll. Increases in response-efficacy, self-efficacy, trust in government, and the active search of COVID-19-related information predicted increased app-use intentions. Increases in self-efficacy, intentions, and the active search of COVID-19-related information predicted increased self-reported app use. Risk perceptions, incidence, and death toll were unrelated to both outcomes. Across an aggravation of the pandemic situation, intentions for and app use were primarily related to response-efficacy, self-efficacy, trust in government, and the active search of COVID-19-related information.