COVID-19 developed from the end of 2019 and became a fully-fledged pandemic in the years that followed. There were no effective cures or vaccinations during the outbreak early stage. The Chinese Health Code and Australian COVIDSafe systems were introduced for contact tracing purposes and to stop COVID-19 spread. Chinese residents widely adopted and used the Health Code, and the COVIDSafe app initially had a high volume of downloads but few active users. We gathered data from various secondary sources e.g. government documents, government websites, academic papers etc., to better understand the Health Code and COVIDsafe functions and technical features. We adapted the UTAUT model to analyse and understand performance expectancy, effort expectancy, social influence and facilitating conditions as determinants of adoption for the comparison of both apps. We seek to highlight potential reasons for different digital adoption outcomes in differing cultural contexts under mandatory and voluntary conditions.