Importance of mitigation measures for hospital transmission of SARS-CoV-2 at the onset of the epidemic: the experience of Brescia, Northern Italy

Purpose: Since the first Italian case of SARS-CoV-2 was detected in Lombardy (Northern Italy) Italy quickly became one of the worst-affected European countries, with a severe impact on health-care workers (HCWs). In the first epidemic, HCWs accounted for 12% of all national COVID-19 cases. We evaluated the burden of COVID-19 among HCWs and other non-health-care workers (nHCWs) in a large Italian hospital. Methods: From March 1st to May 31st 2020, we performed a retrospective study at ASST Civil Hospital, in the Province of Brescia, Lombardy. The study population included all hospital personnel (n = 9265), categorized by professional status. Results: A SARS-CoV-2 test was performed in 3572 workers (38.5%), with a positive result in 552 (5.9% of all hospital personnel). The temporal trend of SARS-CoV-2 cases in hospital staff broadly reflected that in the community, with a great majority of infections occurred during March 2020 (87.7%). From April onward, a steep decrease of positive cases was observed among hospital personnel, while in the community the decrease was much slower. Medical doctors (8.9%) and nurses (8.5%) were the most affected professional categories with a significantly higher risk of SARS-CoV-2 infection (OR 1.436 and OR 1.410, respectively p < 0.0001). HCWs in COVID-19 units presented a significantly higher risk of infection compared to HCWs in non-COVID units (p < 0.001). Conclusion: HCWs were severely affected by the COVID-19 epidemic, probably associated with an overwhelming burden of work and lack of preparedness in prevention of nosocomial transmission of the infection. The rapid decrease of COVID-19 spread in the hospital, registered before the one in the community, suggests that the adopted preventive measures were effective.