Dr Bader raises an important issue that was the subject of some controversy for several years1,2 following the introduction of live attenuated virus mumps vaccine in the United States in December 1967. In retrospect, routine use of the mumps vaccine as soon as it was introduced might have prevented the circumstances that have led to the relative resurgence in mumps recently observed. Most expert opinions at the time of vaccine licensure, and for approximately ten years thereafter, did not recommend priority be given to mumps vaccination. Low priority for mumps vaccination was the result of a variety of factors, including doubts about the duration of immunity conferred by mumps vaccine in the absence of long-term efficacy data and a lack of epidemiologic data on the health impact of mumps that were as convincing as, for example, those for poliomyelitis, rubella, and measles.2 In the absence of strong recommendations,