An employee at Ristorante La Buca has hepatitis A, potentially exposing people who ate at the Center City restaurant at any point from Oct. 28 through lunchtime on Friday, the Philadelphia Department of Public Health announced.

The risk of infection is low, but any customers from that period should be vaccinated against the virus if they have not been, department officials said. Those who have previously been ill with the disease do not need vaccination.

Hepatitis A is a viral infection of the liver. It can be spread by infected people who prepare food if they fail to wash their hands thoroughly after using the bathroom.

People who are infected typically become ill from two to six weeks after exposure. Symptoms can include diarrhea, vomiting, and, in severe cases, jaundice.

The virus also can be spread by drug users who share needles and people experiencing homelessness who lack access to sanitation.

The city typically sees two to six cases of hepatitis A per year. As of August, the health department said there had been 154 cases in 2019, prompting Health Commissioner Thomas Farley to declare a health emergency and increase vaccination efforts.