ABSTRACT Data from digital technologies are increasingly integrated in public health research. In April of 2020, we interviewed a subset of participants who completed a survey approximately one month earlier. Using the survey, we contacted and interviewed participants who had expressed their willingness or unwillingness to share digital data for use in public health. We followed a directed content analysis approach for the analysis of the interview data. Among participants who had reported being unwilling to share data, concerns about privacy, (...) confidentiality, and the purpose of the research were cited. During the interviews, 76.9% of the participants who had who had previously indicated that they were unwilling to share their data, expressed willingness to share data in order to assist with COVID-19 prevention. Our results contribute to our understanding of people’s perspectives on sharing personal data and of the way their perspectives can vary as a function of potential uses of their personal information. (shrink)