This comes just a week after Mets pitcher Noah Syndergaard contracted the illness.
Hand, foot and mouth disease, also known as Coxsackie virus, is rare, minor and most often found in children. It causes fever and a rash on the hands, feet and mouth, as the name suggests. Symptoms typically last two or three days.
Syndergaard’s case was reportedly tied to his visit to a children’s camp.
The Yankees acquired Happ from the Blue Jays just five days ago.
Chris Sale placed on disabled list with mild left shoulder inflammation