To capture the dynamics and impact of the virus spread in the Luxembourgish population, data and sample collection is done every two weeks for two months (4 times in total) with a final follow-up one year after the participant's inclusion in the study. Participants complete questionnaires before each sample collection. The baseline questionnaire captures demographic data, medical history, behavioral and psychological data, and socio-economic status. Participants provided information on medical history, history of allergies, smoking, and chronic medication taken regularly. COVID-19-related data and environmental conditions of the household were obtained.