The Diaries of a Pandemic (COVID-19) collect daily information, through online questionnaires (https://diariosdeumapandemia.inesctec.pt/), on the individual experiences of a large sample of people between 16 and 89 years of age. These participants agreed to provide information on how they are living their daily lives in the context of the pandemic, and on how they act with regard to a set of situations that may influence the course of the Epidemic in Portugal. From a technical point of view, the Diaries of a Pandemic can be seen and analysed as a longitudinal study (a panel survey), with daily follow-up of a dynamic sample of participants. Due to its design, it allows for the estimation of the incidence rate of a wide set of new events, measured in relation to the experience of risk in person-time units. Questionnaires cover the following topics: 1. Test, diagnosis and symptoms; 2. Healthcare use; 3. High-risk contacts; 4. Daily activities; 5. Psychological well-being; and 6. Eating habits and physical activity.