Potential environmental transmission routes of SARS-CoV-2 inside a large meat processing plant experiencing COVID-19 clusters

Abstract

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.

Meta-Analysis of COVID-19 Spread in Meat Processing Plants and Recommended Practical Actions

“…The cutting and deboning areas contained 21% and 50% of the positive SARS-CoV-2 tests among the employees, respectively. Moreover, 3 out of 22 surface samples in productive sections and 3 out of 17 samples in non-productive areas demonstrated active presence of SARS-CoV-2 on high-touch tools in slaughterhouses (39). It was also revealed that mean indoor air temperature was around 6 °C in MPPs.…”

“…The majority of infected employees were mainly from ethnic minority workers and migrants (38). About 40% (66 employees) of infected people consisted of Romanian and Polish workers in pig processing facilities in Netherlands (39). The cutting and deboning areas contained 21% and 50% of the positive SARS-CoV-2 tests among the employees, respectively.…”

“…A study in the Netherlands reported less significant levels of SARS-CoV-2 through air samples of cooled environments in slaughterhouses. Moreover, active viruses were detected through stationary atmospheric samples from the area with COVID-19 hotspots in MPPs (39).…”