"My team called me the office canary. Open-plan office, 40 people — I was first out every time anything went around. I added this to my morning and evening routine 11 weeks ago. Two office outbreaks since. Half the floor out both times. I didn't miss a day." — Diane, 54
"My daughter had her third baby last spring. I went to help for two weeks. Both older kids in daycare bringing something home every few days. My son-in-law got sick. My daughter got sick. Both grandkids had it. I was holding sick babies and sleeping next to a coughing toddler. I'd started this about a month before. Came home and my husband said, 'I can't believe you're not sick.' Neither could I." — Patricia, 61
"Two kids in elementary school. I was sick almost every month — whatever they brought home, I caught within a week. Missing work. Missing my older one's basketball games. I've been using this since September. A stomach bug went through both classrooms in January. My husband caught it. I didn't. First winter in years I haven't lost a week." — Linda, 42
"Sinus infections two or three times a year. Two rounds of antibiotics last winter alone. A nurse in my book club told me about this. Three weeks in, the office flu went around. Eight people out. I kept working. My ENT asked me what I was doing differently." — Margaret, 62