A shutdown of the giant Smithfield Foods meatpacking plant in Sioux Falls, S.D., reverberated across Midwest farms amid rising concern that slaughterhouses have become crucibles for the spread of coronavirus.

At least 80 people had been sickened, the most concentrated COVID-19 outbreak in South Dakota, by Wednesday. Company executives Thursday decided to close the plant for three days.

While the disruption is a problem for hog farmers, there's no sign yet it will lead to food shortages. Even as Smithfield announced the closure, chief executive Kenneth Sullivan pledged to get the Sioux Falls plant going again.

"As an industry and as a nation, it is imperative that we continue to operate our feed mills, farms, plants and distribution centers," Sullivan said in a statement. "Not operating is not an option. People need to eat."

More than 20,000 pigs are butchered daily at the plant, sourced from farmers in a hog-rich region of the Corn Belt that includes southwest Minnesota, northwest Iowa and South Dakota. About 3,700 people work at the plant, one of the nation's largest pork processing facilities.

It's one of several packers, including a Tyson pork plant in southeast Iowa and a large Cargill beef facility in eastern Pennsylvania, closed because of virus outbreaks among workers.

At the Cargill plant in Hazleton, Pa., there were 164 diagnosed cases of COVID-19, said Wendell Young, president of United Food and Commercial Workers (UFCW) Local 1776, which represents 800 workers there.

"The number that is even scarier is the many more who are sick and waiting for their test results," Young said. He estimated that when the Hazleton plant closed, 150 to 200 people were calling in sick.

'People are elbow to elbow'

Cargill's Hazleton plant doesn't include a slaughterhouse. The facility takes in large boxed meat cuts and workers process them into steaks, roasts and hamburger for supermarkets. A good portion of that work is done by employees wielding saws and knives.

"This is a huge challenge," Young said. "In a lot of parts of a plant, people work in close contact. People are elbow to elbow on the production floor."

Minnetonka-based Cargill said it learned from its experience in China and began temperature testing U.S. employees where it could in late February. It's also working to provide masks to employees.

Young said all four of the Pennsylvania meat plants represented by his UFCW local have been idled over the past two weeks due to COVID-19, including a huge JBS beef slaughterhouse and processing facility in the southeastern town of Souderton. Young said Local 1776's chief shop steward at the JBS plant died from the illness.

The counties hosting both the JBS and the Cargill plants have among the highest number of confirmed COVID-19 cases in Pennsylvania, according to the state.

In other states, unions are pressing meat processors to do more to protect employees.

The Retail, Wholesale and Department Store Union, which represents poultry workers, charged that a poultry processing plant in Georgia was late to provide workers there with protective equipment. Employees have been asked to "debone chickens elbow to elbow with no access to masks," the union said; several workers are sick and two have died from COVID-19.

A pork plant in Sioux City, Iowa, run by Seaboard Foods, said it sought to buy masks for workers after the Centers for Disease Control and Prevention revised its guidance to recommend masks last Friday, but by Wednesday they had not arrived.

Workers at many packing plants do wear goggles and hairnets that also cover their mouths.

A tight supply, disrupted

The pork industry slaughters 500,000 hogs per day in the United States, and the supply chain from pregnant sow to the consumer is tightly calibrated.

Hog prices have plunged because of the nationwide shutdown of the food service industry. Now U.S. farmers have hundreds of thousands of pigs hitting market weight each day, more pigs coming up behind them and reduced processing capacity.

"If it's just a demand problem then you can harvest the pigs and put the meat into freezers," said Lee Johnston, an animal science professor at the University of Minnesota, Morris who specializes in swine production. "But if we get to the point where the blockage is at the packing plant, then the challenge is we've got live pigs on farms around the country that are still eating, still growing. How do we manage that?"

Cattle and hog farmers should be able to deal with temporary, scattered meatpacking plant closures, but if the problem spreads and lingers, things will get more difficult. The worst prospect for farmers — financially and emotionally — is euthanizing pigs.

"I can't just turn them out on the sidewalk or out to pasture. That ultimately becomes the fear that we all want to avoid," said Terry Wolters, a hog farmer near Pipestone, Minn., and a member of the Pipestone System, a group of 450 farmers who raise hogs together.

"We're highly concerned about the disruption in the harvest capacity, especially if it's extended," he said.

But grocery stores will likely remain well-supplied. Stocks of meat in cold storage were up in February and the industry is retooling to send more meat to grocers instead of food service companies. The U.S. also exports 30% of its pork and, if needed, some of that can be sold domestically.

"I don't foresee that to be a problem at all," Wolters said of the food supply. "The heartland is at work providing food for this country."