The York Region Health Department is warning that thousands of people may have been exposed to hepatitis A at a Tim Hortons outlet in Newmarket.

According to a news release posted on its website, the chief medical officer of health, Dr. Karim Kurji, is advising customers "who visited the Tim Hortons location at 16545 Yonge Street … that they may have been exposed to hepatitis A if they consumed food from this establishment between Thursday, April 2 and Wednesday, April 22, 2009."

Two employees tested positive for the virus.

Health inspectors say the risk of infection for customers is low but they're taking preventive steps, including holding a vaccination clinic on Monday, April 27, 2009, from 4 p.m. to 8 p.m. in the auditorium of the Newmarket Health Centre, located at 194 Eagle St.

"People eligible for the vaccine are those customers who consumed food from this location anytime between Monday, April 13 and Wednesday, April 22, 2009. People who are unable to attend the clinic can receive the vaccine from their health care provider," said the municipality in a news release.

Hepatitis A is rarely fatal. Its symptoms may include fever, a feeling of being unwell, loss of appetite, diarrhea, nausea and abdominal discomfort.

"The symptoms may appear two to seven weeks after exposure, but usually occur about four weeks after exposure. People who have pre-existing liver problems, especially those who have hepatitis C, can become extremely ill if they contract hepatitis A. Anyone who experiences these symptoms should see their doctor," said the release.

Inspectors say customers who only consumed drinks from the outlet are at very low risk of contracting the virus. Only customers who purchased food from the store should be concerned.