Dozens of U.S. meat-processing plants have been forced to close temporarily as the industry struggles to contain the spread of the coronavirus among employees who often stand side-by-side while cutting and packaging beef, pork and poultry. Giant slaughterhouses that employ thousands of people are designed to have workers close together, making it difficult to adhere to social distancing guidelines that advise people to stay 6 feet apart. Even as companies take steps to protect workers, industry experts say it’s nearly impossible to eliminate all risk of catching the virus and they note safety measures have been adopted unevenly.