During this period, 340 eggs were collected from 4 immunized chickens and thus, a total of ~2,400 mg specific anti-NoV IgY was obtained. Producing an equal amount of antibody would require 100-125 guinea pigs assuming that 15-20 ml sera can be collected from each animal. Strikingly, high levels of antigen-specific egg yolk IgY can be produced up to 2 years when the bird is continuously boosted every three months. Furthermore, collection of yolk antibody is non-invasive without affecting the immunized chickens. Finally, the NoV-specific IgY showed excellent reactivity at a wide range of temperature and pHs (this report), an indication of highly stable IgY, important for clinical use