ABSTRACT
Healthcare-related SARS-CoV-2 infection is an issue of particular concern during the pandemic. It has important repercussions on the National Health System, which represents a source of medical-legal health disputes. In the healthcare context, there are reports of negative screening at hospital admission (via nasopharyngeal swabs) and subsequent diagnosis of SARS-CoV-2 infection during hospitalization. Such cases cannot be considered a priori of healthcare-related infections but require extensive in-depth evaluation. In this study, we propose an empirical classification to frame cases of SARS-CoV-2 infection diagnosed in the hospital (first negative admission swab, with subsequent positive test during hospitalization). The classification is based on five categories: nosocomial, probably nosocomial, indeterminate, probably community, and community cases. We analyzed patients who died after testing positive for SARS-CoV-2 during hospitalization (with initial negative screening) in the largest hospital in Northwest Italy from February 2020 to 31 December 2021. A total of 383 cases were tracked and are listed as follows: 41 cases (11%) were classified as nosocomial (i.e., 3.2% of COVID-19 deaths). In contrast, 71 cases (19%) were classified as probably nosocomial, 69 (18%) were indeterminate (i.e., the clinical, radiological, and laboratory characteristics did not provide information on the genesis of the infection), 166 (43%) were classified as probably community cases, and 36 (9%) were defined as community cases. Deceased patients with nosocomial SARS-CoV-2 infection constituted the following: 3.23% (41/1266) with respect to the total number of COVID-19 deaths, 1.1% (41/3789) with respect to those who entered the hospital with a negative swab and 0.82% (41/4672) with respect to the total of deaths from any cause of death. In this paper we discuss the topic and issues of nosocomial COVID-19 in hospitalized patients and address the medicolegal implications.