Baldachin: Ceiling HEPA-filtration to Prevent Nosocomial Transmission of COVID-19

In this study, a patient space occupied by a patient with confirmed COVID-19 in an open-space multiple bed area in the Intermediate Care Unit will be equipped with a mobile, optimally placed high efficiency particulate air ("HEPA")-equivalent air filtration unit ("Baldachin") in addition to existing hospital policy infection prevention and control measures. The investigators are going to evaluate this intervention regarding its capacity to prevent the nosocomial onwards transmission of Sars-COV2 to patients located in the same multiple-bed open space patient area.

SARS-CoV-2 transmission includes a considerable amount of long-distance aerosol transmission. Ideal isolation is in single rooms. Isolation in special care multiple bed open-space patient areas (e.g. in the Intensive and Intermediate Care Unit) is set back to onsite isolation with distancing and ventilation as partial mitigation measures against nosocomial transmission. The investigators want to assess the effect of supplementation of existing room ventilation by means of an optimally placed mobile high efficiency particulate air ("HEPA") filtration unit ("Baldachin") in the ceiling area over confirmed COVID-19 infected patients on nosocomial onwards transmission to patients located in the same open-space multiple bed area. In order to quantify the effect, the investigators will determine the proportion of nosocomially infected individuals as assessed by nasopharyngeal swab on day 4 after the last exposure amongst all in the same room exposed patients in cardiovascular open-space Intermediate Care Unit rooms with "Baldachin" vs. open-space Intermediate Care Unit rooms without "Baldachin".