RESUMEN
Worldwide exceptionally many COVID-19 clusters were observed in meat processing plants. Many contributing factors, promoting transmission, were suggested, including climate conditions in cooled production rooms favorable for environmental transmission but actual sampling studies are lacking. We aimed to assess SARS-CoV-2 contamination of air and surfaces to gain insight in potential environmental transmission in a large Dutch meat processing plant experiencing COVID-19 clusters. We performed SARS-CoV-2 screening of workers operating in cooled production rooms and intensive environmental sampling during a two-week study period in June 2020. Sampling of air (both stationary and personal), settling dust, ventilation systems, and sewage was performed. Swabs were collected from high-touch surfaces and workers hands. Screening of workers was done using oronasopharyngeal swabs. Samples were tested for presence of SARS-CoV-2 RNA by RT-qPCR. Of the 76 (predominantly asymptomatic) workers tested, 27 (35.5%) were SARS-CoV-2 RNA positive with modest to low viral loads (Ct[≥]29.7). In total, 6 out of 203 surface swabs were positive (Ct [≥]38), being swabs taken from communal touchscreens/handles. One of the 12 personal air samples and one of the 4 sewage samples were positive, RNA levels were low (Ct[≥]38). All other environmental samples tested negative. Although one-third of workers tested SARS-CoV-2 RT-PCR positive, environmental contamination was limited. Hence widespread transmission of SARS-CoV-2 via air and surfaces was considered unlikely within this plant at the time of investigation in the context of strict COVID-19 control measures in place.
RESUMEN
Unprecedented SARS-CoV-2 infections in farmed minks raised immediate concerns regarding human health which initiated intensive environmental investigations. Air sampling was performed in infected mink farms, at farm premises and at residential sites. A range of other environmental samples were collected from minks housing units including bedding material. Inside the farms, high levels of SARS-CoV-2 RNA were found in airborne dust, on surfaces, and on various other environmental matrices. This warns for occupational exposure which was substantiated by considerable SARS-CoV-2 RNA concentrations in personal air samples. Dispersion of SARS-CoV-2 to outdoor air was found to be limited and SARS-CoV-2 RNA was not detected in air samples collected beyond farm premises, implying a negligible environmental exposure risk for nearby communities. Our occupational and environmental risk assessment is in line with whole genome sequences analyses showing mink-to-human transmission in farm workers, but no indications for direct zoonotic transmission events to nearby communities.
RESUMEN
In April 2020, respiratory disease and increased mortality were observed in farmed mink on two farms in the Netherlands. In both farms, at least one worker had been found positive for SARS-CoV-2. Necropsies of the mink revealed interstitial pneumonia, and organ and swab samples tested positive for SARS-CoV-2 RNA by qPCR. Variations in viral genomes point at between-mink transmission on the farms and lack of infection link between the farms. Inhalable dust in the mink houses contained viral RNA, indicating possible exposure of workers.