Fig. 1

Selection procedure of hospital visits included in the analysis. The full database included hospital visits in conventional hospital wards, day-care units, and in the emergency room. In case of repeated consecutive tests during the same hospital visit, only the first positive PCR test was considered. The subset database included only hospital stays in conventional wards, for years 2014–2022 (infection control indicators were not available for year 2023 at time of data analysis)