DES MOINES, Iowa (AP) — A northwest Iowa county that is home to a meatpacking plant has seen nearly 500 coronavirus cases in the past week, but state officials and the company said Wednesday they couldn't confirm an outbreak at the facility.

The state health department reported 678 cases since Wednesday in Buena Vista County, where a Tyson pork processing plant is located in Storm Lake.

Iowa Gov. Kim Reynolds said the state hasn’t confirmed an outbreak related to the plant but that testing is underway “to make sure we are understanding the scope of what that is and how we can start to isolate those testing positive.”

Tyson spokeswoman Liz Croston said the company and local health officials have conducted large-scale testing in Storm Lake and “will disclose verified test results once complete data is available.”

State officials haven’t always publicly released meat processing plant outbreaks unless they’re asked specifically about certain locations by reporters, as was the case with recent outbreaks at a Perdue Farms pork processing facilities in Sioux City and Sioux Center.

“We’ve been announcing them at these press conferences as the questions have been asked,” said Sarah Reisettersaid, deputy director of the Iowa Department of Public Health.

The department doesn’t consider that a company has had an outbreak until at least 10% of employees have tested positive for the coronavirus, Reisetter said.

“Sometimes it takes us a little bit of time to pull together the information to understand whether there has been an outbreak in a particular facility,” she said.

Iowa health data indicated 595 new positive cases statewide on Wednesday for a total of 18,256 known cases of coronavirus infection. The state reported 21 more deaths for a total of 485 deaths.