Four age groups were formed to capture young adulthood, different stages of middle age, and the ages of an increased risk of severe COVID-19 infection: 18–29, 30–44, 45–64, and 65 years and older.
Educational levels according to the CASMIN classification (“Comparative Analyses of Social Mobility in Industrial Nations”) were used as an indicator of socioeconomic status (96 ). Three groups with low, medium, and high levels of education are distinguished on the basis of school and vocational qualifications.