On Friday afternoon, the front of Shake Shack was covered in a thick sheet of plastic and surrounded by workers wearing hazardous material suits.

Shake Shack closed down on Wednesday evening after an employee called in sick with flu-like symptoms, according to Bryan Murphy Shake Shack’s general manager for the local market. In response to the call, the restaurant hired workers to spray the area in and around Shake Shack to rid it of any potential disease. Following visits from a team of cleaners and a health inspector, the establishment reopened on Saturday morning.

“They wanted to have it closed preventatively,” said Paul Kowalski, acting director of health for the New Haven Health Department. “I think they were afraid it might have been norovirus.”

Shake Shack does not know what caused the employee’s sickness, said Thomas Lerou, assistant manager for Shake Shack’s New Haven location. The restaurant was closed as a precautionary measure to make sure the symptoms were not the result of a more serious problem, he said.

The decision to close the restaurant was a collective decision made by Shake Shack management after receiving the call, Edwin Bragg, public relations coordinator for Shake Shack, said in an email.

After receiving a call from their employee, Shake Shack notified the New Haven Health Department that they would be closing that afternoon, said Bryan Murphy, Shake Shack’s general manager for the local market.

Usually the health department forces an inspection, but in this instance Shake Shack contacted the Health Department with the potential problem, Kowalski said. He added that this is “not very common.”

“This is the first time we’ve ever had someone close before they were told to close,” Kowalski said. “They did it on a preventative basis and I appreciated it.”

It is not Shake Shack’s official policy to shut down the restaurant when an employee is ill, but the manager made the call just to be safe, Murphy said.

They contacted the Health Department first to keep them informed of the potential health risk so the department was not left speculating, he added.

“It’s not a policy,” Murphy said. “It’s just something we didn’t want to mess around with.”

The restaurant hired a private company to clean the location on Friday before calling in health inspectors to examine it the next morning, Murphy said.

After visiting the restaurant, the health inspector found no traces of virus at the location, Kowalski said.

“[The health department] said we were clean,” Lerou said. “They seemed excited to get a heads-up from us.”

Murphy said he does not expect the restaurant’s closing to effect future business.

Over half of the 12 Yale students interviewed said they were unaware Shake Shack had closed temporarily for cleaning.

Paolo Roxas ’17 said the closure speaks well of Shake Shack’s health standards.

Other local restaurants have not reported similar symptoms amongst their employees, Kowalski said.

Shake Shack opened on Chapel Street in September 2012.