Demi, Madonna, Gwyneth Paltrow, Salma Hayek and anyone else who hit Ashton Kutcher's Feb. 7 birthday party at Socialista is being advised to now line up a gamma globulin shot, seeing as one of the barkeeps on duty that night has been diagnosed with hepatitis A.

"Although no additional cases of illness have been identified, the [New York City] Department of Health is urging customers to get the vaccination as a precautionary measure," a spokesperson for the NYC hotspot tells TMZ. "We are grateful for their efforts and we will continue to support them in every way possible."

And here you thought the worst you'd leave the party with was Bruce Willis' phone number.