The vaccine is only about 90% effective when given to a person twice in their lifetime (as recommended). FYI, there is also a whistleblower claim/lawsuit going on against the largest manufacturer of the MMR vaccine (Merck) alleging that the effectiveness claims have been overstated and may not even be 90%.... That being said, they should be doing a better job of sanitizing locker rooms knowing that this is a problem in the NHL....