Age, co-morbid conditions, sex, and race were ascertained from participant interview. Recent chemotherapy, radiation therapy, or use of immunomodulating medications were ascertained by self-report or chart review. CDC-defined high risk medical conditions were identified by self-report of organ transplantation, cancer, diabetes mellitus, splenectomy (functional or anatomic), cardiovascular disease, renal disease, sickle cell disease, chronic pulmonary disease, seizure disorder, immune deficiency, or dementia.2 Self-reported stress was determined by asking participants to respond yes or no to the question "Have you suffered psychological stress or acute disease in the past 3 months?" included as part of the Mini Nutritional Assessment Questionnaire.3 Height and weight were measured by research study staff and body mass index (BMI) was calculated as weight (kg) / height (m)2.