Bioaerosol sampling for SARS-CoV-2 in a referral center with critically ill COVID-19 patients March-May 2020.

Background Previous research has shown that rooms of patients with COVID-19 present the potential for healthcare-associated transmission through aerosols containing SARS-CoV-2. However, data on the presence of these aerosols outside of patient rooms are limited. We investigated whether virus-containing aerosols were present in nursing stations and patient room hallways in a referral center with critically ill COVID-19 patients. Methods Eight National Institute for Occupational Safety and Health BC 251 two-stage cyclone samplers were set up throughout six units, including nursing stations and visitor corridors in intensive care units and general medical units, for six hours each sampling period. Samplers were placed on tripods which held two samplers positioned 102 cm and 152 cm above the floor. Units were sampled for three days. Extracted samples underwent reverse transcription polymerase chain reaction for selected gene regions of the SARS-CoV-2 virus nucleocapsid and the housekeeping gene human RNase P as an internal control. Results The units sampled varied in the number of laboratory-confirmed COVID-19 patients present on the days of sampling. Some of the units included patient rooms under negative pressure, while most were maintained at a neutral pressure. Of 528 aerosol samples collected, none were positive for SARS-CoV-2 RNA by the estimated limit of detection of 8 viral copies/m 3 of air. Conclusion Aerosolized SARS-CoV-2 outside of patient rooms was undetectable. While healthcare personnel should avoid unmasked close contact with each other, these findings may provide reassurance for the use of alternatives to tight-fitting respirators in areas outside of patient rooms during the current pandemic.