These sources contained information from before and/or during the epidemic.
Three data sources were used for this study: the Public Health Monitor published by the Community Health Services, Association of Regional Public Health Services and Regional Medical Emergency Preparedness and Planning offices, RIVM and Statistics Netherlands; the Lifelines cohort-and Corona Research Initiative conducted in the northern Netherlands; and the Corona Behavioural Unit COVID-19 cohort coordinated by RIVM. These sources contained information from before and/or during the epidemic.