key: cord-0953716-cjt2y67m authors: Horve, P. F.; Dietz, L.; Fretz, M.; Constant, D. A.; Wilkes, A.; Townes, J. M.; Martindale, R. G.; Messer, W. B.; Van Den Wymelenberg, K. title: Identification of SARS-CoV-2 RNA in Healthcare Heating, Ventilation, and Air Conditioning Units date: 2020-06-28 journal: nan DOI: 10.1101/2020.06.26.20141085 sha: 22a901d6439bf8bd327e9d1b96a2e2a0faca8502 doc_id: 953716 cord_uid: cjt2y67m Available information on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission by small particle aerosols continues to evolve rapidly. To assess the potential role of heating, ventilation, and air conditioning (HVAC) systems in airborne viral transmission, this study sought to determine the viral presence, if any, on air handling units in a healthcare setting where Coronavirus Disease 2019 (COVID-19) patients were being treated. The presence of SARS-CoV-2 RNA was detected in approximately 25% of samples taken from nine different locations in multiple air handlers. While samples were not evaluated for viral infectivity, the presence of viral RNA in air handlers raises the possibility that viral particles can enter and travel within the air handling system of a hospital, from room return air through high efficiency MERV-15 filters and into supply air ducts. Although no known transmission events were determined to be associated with these specimens, the findings suggest the potential for HVAC systems to facilitate transmission by environmental contamination via shared air volumes with locations remote from areas where infected persons reside. More work is needed to further evaluate the risk of SARS-CoV-2 transmission via HVAC systems and to verify effectiveness of building operations mitigation strategies for the protection of building occupants. These results are important within and outside of healthcare settings and may present a matter of some urgency for building operators of facilities that are not equipped with high-efficiency filtration. It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. . https://doi.org/10.1101/2020.06.26.20141085 doi: medRxiv preprint 3 47 Abstract: 48 Available information on Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) 49 transmission by small particle aerosols continues to evolve rapidly. To assess the potential role CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) Since its emergence in late 2019, SARS-CoV-2 has spread across the globe and led to the deaths 72 of over 450,000 individuals 1 . The main mechanism of transmission has been identified as 73 respiratory droplet transmission by symptomatic or asymptomatic persons 2-6 . Despite the 74 identification of droplet spread as the most common mechanism of transmission 6 , recent studies 75 suggest that air movement patterns indoors induced through heating, ventilation, and air 76 conditioning (HVAC) systems may contribute to transmission events 7,8 . Aerosolized SARS-CoV-2 RNA has been previously detected in the air of hospital rooms with 79 symptomatic COVID-19 patients 9-11 , suggesting the possibility that SARS-CoV-2 viral RNA 80 (and potentially virus) have the capacity to enter into building HVAC systems in evacuated room 81 air after a shedding or aerosolization event from infected individuals. Although hospitals contain 82 higher levels of mechanical filtration and room air exchange than almost all other buildings, 83 which are important strategies to help prevent the transmission of disease, a growing body of 84 evidence suggests that these precautions may not be adequate to completely eliminate SARS-85 CoV-2 12-14 in filtered air. Studies have shown the persistence of SARS-CoV-2 in air to be hours 86 and on surfaces, days 15 . Efforts to limit the transmission and continued spread of SARS-CoV-2 87 have mainly focused on social (spatial) distancing, increased cleaning regimens, mandated face 88 coverings, and increased surveillance 15,16 . However, as more indoor spaces begin to reopen and 89 increase in occupant density, more individuals will occupy shared air spaces serviced by HVAC CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted June 28, 2020. . https://doi.org/10.1101/2020.06.26.20141085 doi: medRxiv preprint aimed to reduce SARS-CoV-2 transmission and thereby the number of COVID-19 cases. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. In total, 56 samples from three different AHUs were collected; 25% (14/56) of samples 156 contained detectable SARS-CoV-2 RNA (Table S1 ). The highest abundance sample (~245 gene 157 copies) was found on the pre-filters, where outside air mixes with recirculated building air. Of CoV-2 RNA ( Table 1 ). The least SARS-CoV-2 RNA was detected at the final filter and the most 161 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. . https://doi.org/10.1101/2020.06.26.20141085 doi: medRxiv preprint even after the filtration process and the dilution from the addition of 70-80% outside air, ( thus, 183 only 20-30% recirculated air, during the sampling period). Previous studies have demonstrated that SARS-CoV-2 can be found in aerosols and droplets 212 ranging from 0.25-4 microns 10, 11 . In experimentally generated aerosols, SARS-CoV-2 has been 213 demonstrated to retain infectivity for between one and sixteen hours 29-32 , lending credence to the 214 potential for aerosolized transmission to occur. There are steps that can be taken to limit the potential impact of airborne dissemination of CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted June 28, 2020. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted June 28, 2020. Does COVID-19 Spread Through Droplets 262 Alone? Front Public Health Transmission of SARS-CoV-2 by inhalation of 265 respiratory aerosol in the Skagit Valley Chorale superspreading event A familial cluster of pneumonia associated with the 269 2019 novel coronavirus indicating person-to-person transmission: a study of a family Aerodynamic analysis of SARS-CoV-2 in two Wuhan 294 hospitals Airborne route and bad use of 296 ventilation systems as non-negligible factors in SARS-CoV-2 transmission Split Air Conditioners and their role in Airborne Infection Spread: Short 300 Association of infected probability of COVID-19 with ventilation rates in 303 confined spaces: a Wells-Riley equation based investigation. Emergency Medicine Identifying airborne transmission as the 306 dominant route for the spread of COVID-19 COVID-19 and the re-opening of 309 schools: a policy maker's dilemma Effects of air temperature and 357 relative humidity on coronavirus survival on surfaces Survival of human coronaviruses 229E and OC43 in 360 suspension and after drying onsurfaces: a possible source ofhospital-acquired infections CoV-2 as Compared with SARS-CoV-1 the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)The copyright holder for this preprint this version posted June 28, 2020. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted June 28, 2020. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)The copyright holder for this preprint this version posted June 28, 2020. . https://doi.org/10.1101/2020.06.26.20141085 doi: medRxiv preprint