In times of increasing digitization, the protection of individual data privacy becomes more important than ever before. To craft privacy policies that do not only meet legal requirements, but also address the public’s concerns, understanding individual privacy attitudes is key. Previous research suggests that privacy attitudes depend on a set of parameters related to the data type, data collector and other situational characteristics. However, the importance of single situational characteristics may possibly be altered by changes in the environment. This circumstance becomes apparent and even more important with the outbreak of the COVID-19 pandemic. The pandemic constitutes an exceptional situation in which individuals may be willing to transmit more personal data than usual for the sake of public health and safety. In this study, we analyze how attitudes towards acceptable data use shift in times of crisis. In July 2019, long before the pandemic, we conducted a survey in Germany in which we measured respondents’ acceptance of the collection and use of health data for public health purposes including preventing the spread of a virus. As the pandemic set in, we replicated this survey in the spring of 2020 to investigate changes in respondents’ willingness to share data for public health purposes in response to the crisis. Using data from 3,502 respondents, we demonstrate and quantify the shift in privacy attitudes with situational characteristics. Public acceptance of the use of personal health data to combat an infectious disease outbreak increased notably, while acceptance of personal data use in several other scenarios barely changed over time. We conclude that policymakers need to carefully consider the intended purpose of and appropriate limitations on data use for public health and argue that the design of data collection tools should meet both public health and privacy concerns.