A vaccine clinic is being held at the University of Kentucky after three students tested positive for mumps and several others reported symptoms.

University Health Services said in a statement that a walk-in clinic is being held Wednesday for students who haven’t had the MMR vaccine.

Health Services Director of Nursing Mindy Scott told WKYT-TV that the most effective way to prevent mumps is with two doses of the MMR vaccine. She said those who haven’t been vaccinated, those who have gotten only one dose of the vaccine, or those who don’t know if they’ve been vaccinated should come in.

Scott said it’s still possible to get mumps after being vaccinated, but the symptoms are usually less severe.