Investigation of Nosocomial SARS-CoV-2 Transmission from Two Patients to Health Care Workers Identifies Close Contact but not Airborne Transmission Events

OBJECTIVETo describe the pattern of transmission of SARS-CoV-2 during 2 nosocomial outbreaks of COVID-19 with regard to the possibility of airborne transmission.DESIGNContact investigations with active case finding were used to assess the pattern of spread from 2 COVID-19 index patients.SETTINGA community hospital and university medical center in the United States, in February and March, 2020, early in the COVID-19 pandemic.PATIENTSTwo index patients and 421 exposed health care workers.METHODSExposed staff were identified by analyzing the EMR and conducting active case finding in combination with structured interviews. Staff were tested for COVID-19 by obtaining oropharyngeal/nasopharyngeal specimens, with RT-PCR testing to detect SARS-CoV-2.RESULTSTwo separate index patients were admitted in February and March 2020, without initial suspicion for COVID-19 and without contact or droplet precautions in place; both patients underwent several aerosol generating procedures in this context. A total of 421 health care workers were exposed in total, and the results of the case contact investigations identified 8 secondary infections in health care workers. In all 8 cases, the staff had close contact with the index patients without sufficient personal protective equipment. Importantly, despite multiple aerosol generating procedures, there was no evidence of airborne transmission.CONCLUSIONThese observations suggest that, at least in a healthcare setting, a majority of SARS-CoV-2 transmission is likely to take place during close contact with infected patients through respiratory droplets, rather than by long-distance airborne transmission.