Identifying medical professionals at risk for in-hospital COVID-19 infection: a snapshot during a "tsunami" highlighting unexpected risks

The aim of this study was to profile healthcare professionals (HCPs) who infected with COVID-19 in hospital while working in a COVID-19 hub hospital during the pandemic. A questionnaire was sent to all HCPs from whom nasopharyngeal swabs (NPS) were collected. The type of work, work environment, individual characteristics, and modality of infection were analyzed. Working areas were categorized into COVID-free areas (wards and ICUs for patients without COVID-19, medical offices, and hospitality counters) and COVID+ areas (dedicated wards and the ICU for patients with COVID-19). From March 1 to 20, 2020, 302 HCPs were tested: 251 (83.1%) responded to the questionnaire, but 9 were excluded since infection occurred outside the hospital. The remaining 242 subjects included 53 (21.9%) with positive NPS and 189 (78.1%) with negative NPS, significant differences in NPS results were evident depending on the subject's role (p = 0.028). Pairwise post hoc analysis revealed that surgeons had a significantly increased rate of positive NPS (p = 0.001). Of the 189 subjects with negative NPS, 175 (92.6%) worked in COVID-free areas, and 14 (7.4%) in COVID+ areas. Of the 53 subjects with positive NPS, 44 (83.1%) worked in COVID-free areas and 9 (16.9%) worked in COVID+ areas. Medical offices featuring an open space with adjacent desks were identified as areas of higher risk. An apparent cause of infection could not be identified in 21 (39.6%) subjects with positive NPS. Among a total of 251 subjects, 80 (41.5%) of the 193 subjects with negative NPS and 16 (27.6%) of the 58 subjects with positive NPS had been vaccinated against the common flu. In conclusion, the vast majority of subjects with positive NPS came from COVID-free areas. The source of infection could not be identified in a significant portion of subjects with positive NPS. Personnel need better protection, more testing with NPS needs to be performed, and workplace layouts need to be re-thought. Vaccination against the flu seems to provide some protection.