Chipotle Mexican Grill said Tuesday that the recent norovirus outbreak in a Virginia restaurant was due to a lax enforcement of the company’s sick policy, CNBC reported.

“We conducted a thorough investigation, and it revealed that our leadership there didn’t strictly adhere to our company protocols,” CEO Steve Ells said, adding that the restaurants should have been more aware of employee health issues.

Last week, tests confirmed that a customer who ate at a Chipotle in Sterling, Virginia, contracted norovirus. The Wall Street Journal reported that 133 diners reported being sickened as well, though their cases were not confirmed as norovirus.

It has been about two years since an E. coli outbreak rattled the food chain. In Oct. and Dec. 2015, at least 60 people were infected with the illness after eating at locations across the country. At least 22 people were hospitalized.

Published at 11:25 PM CDT on Jul 25, 2017 | Updated at 5:41 AM CDT on Jul 26, 2017