Survey results of self-reported mumps immunity among workforce, Northwestern Memorial Hospital, Chicago, Illinois, USA, 2006. Results are categorized by high-risk caregivers, those who worked in areas where mumps cases were located or worked with pregnant or immunosuppressed patient populations; low-risk caregivers, those who cared for patients in other inpatient or outpatient areas; or noncaregivers. Compliance with corporate health evaluation and vaccination for those who did not report immuni