When it comes to COVID-19 hotspots none are hotter than US meat and seafood processing plants, where virus outbreaks are hard to contain in the crowded, largely indoor spaces.

The prolonged close workplace contact among workers, shared work spaces, shared transportation to and from the workplace, congregate housing, and frequent community contact with fellow workers are the "distinctive factors" that have led to the rapid spread of the virus to more than 16,000 meat and poultry plant workers in the United States, according to the Centers for Disease Control and Prevention (CDC).