Chipotle’s stock took a nosedive this week after reports emerged on Tuesday that customers in a Sterling, Va. location were vomiting, having diarrhea and experiencing stomach pains — symptoms consistent with norovirus, according to a statement from company CEO Steve Ells. The company temporarily closed the location to sanitize its surfaces and reopened on Wednesday, Ells said.

While Wall Street predicts difficult days ahead for Chipotle’s stock, the outbreak does not appear to be indicative of a larger problem with the restaurant’s food safety, says Niyati Parekh, associate professor of public health nutrition at New York University. The norovirus likely came from one person in the restaurant, not from Chipotle’s food supply, since the illnesses only occurred in a single location, Parekh says. For that reason, people visiting other Chipotle restaurants shouldn’t worry, she says.

“It has nothing to do with the sourcing of the food,” Parekh tells Fortune.

Parekh says the most likely explanation for the outbreak is that a worker at Chipotle was sick and spread the virus by touching food that was sold to customers. According to the Centers for Disease Control and Prevention, most norovirus outbreaks in restaurants stem from infected food workers.

Chipotle has been under scrutiny for its food safety practices since 2015, when the company faced a barrage of foodborne illness outbreaks like E.coli, norovirus and salmonella at locations across the United States. The E.coli outbreaks, which affected more than 50 people across 11 states, were likely connected to an issue in Chipotle’s supply chain, although CDC officials could not pinpoint a specific cause.

In a statement on Tuesday, Jim Marsden, Chipotle’s executive director of food safety, said the virus did not come from the company’s food supply.

“It is safe to eat at Chipotle,” he said.