A surge in COVID-19 cases is starting to impact American meat-processing operations in another potential threat to food supply chains that were upended in the early stages of the pandemic.

JBS SA, the world’s largest meat supplier, has put about 8% of its U.S. unit’s 64,400-person staff on paid leave since coronavirus cases began to accelerate in October, a company spokesman said Friday. At its Greeley plant in Colorado, 202 vulnerable workers were excused from duties.

The plant reported 32 COVID-19 cases among its staff of 3,500 in the most recent wave, while Weld County, where the plant is located, has had more than 4,450 cases, JBS said.

Meat plants are looking to avoid the kind of painful disruptions that marked the first wave of the pandemic when outbreaks among workers prompted shutdowns, supply shortages, livestock gluts and surging consumer prices. The initial outbreak at Greeley was among the most deadly, with six deaths and over 300 cases, according to Food & Environment Reporting Network, a non-profit that tracks outbreaks in America’s food system.

“While we have only seen very limited impacts on production in our facilities, any impact is due to our voluntary removal of vulnerable populations,” JBS USA said in a statement.

JBS said it’s mitigating the impact of removing more than 5,000 vulnerable workers by simplifying the mix of products. Animal slaughter levels in recent months have stayed relatively consistent compared with last year, although some labor-intensive processing tasks such as removing bones from pork hams or beef loins has been delayed as workers focus on essential tasks.

“Labor is tight everywhere,” Altin Kalo, an analyst at Steiner Consulting Group in New Hampshire, said by phone. “They can get the animals dead, but processing them is tough.”

Vaccine Priorities

Increasing rates of infection in much of the U.S. have raised the specter of further disruptions in food industries. During the initial outbreak in the U.S., an estimated 8% of cases were linked to meat plants and subsequent community spread, according to a study by researchers at Columbia University and the University of Chicago. Production of meat and poultry has rebounded after dropping sharply in April. Absent workers continue to impede operations.

Meanwhile, the U.S. meat industry wants its workers to be among the top priority for vaccines once health-care workers and people in long-term care facilities get shots, the North American Meat Institute said Thursday.

Demobilizing older workers doesn’t improve the safety of those still at the plant, said Kim Cordova, head of United Food & Commercial Workers Local 7, who is calling for additional measures such as access to free, daily on-site testing.

“Now it is critical we protect the lives of our Union brothers and sisters in Greeley and across the country because it is the workers that make these companies’ profits possible,” Cordova said.

JBS said it’s actively working with health departments and union partners to coordinate vaccinations as soon as they become available to essential workers. The company said it has implemented free surveillance testing of asymptomatic team members, conducting more than 20,000 tests so far.

The parent company’s shares (JBSAY) closed at $8.83, down 2%.