Researchers reconstructed the likely cause of the outbreak at a Toennies Group slaughterhouse in Rheda-Wiedenbrueck, where about 1,500 workers contracted the virus. Similar conditions at plants globally are a reason they’ve become virus epicenters, according to the report from groups including the Helmholtz Center for Infection Research.

Meat plants from the U.S. to the U.K. and South America have seen the rapid spread of the virus, infecting thousands of employees who often work in close proximity on processing lines. Dozens of workers have died, and labor advocates have said that a lack of social distancing could continue to put people at risk. Outbreaks also forced American meat plants to close earlier this year, sparking some protein shortages.

Meanwhile, China is ramping up testing of imports of cold food for the virus. Even as global scientific experts say that the likelihood of transmission through food is extremely low, the Asian country has slapped export bans on some abattoirs with cases, further fueling the urgency to contain the disease.