The child's immune system reaches full adult-level immunity at 6 YEARS (yes, I'm shouting), not six months. I can provide references when I get to work later today, if anyone wants. There have been no studies of breast milk composition past two years post-partum (nor have I been able to interest any biochemist types in conducting a study, and I *have* tried), so no one really knows what the immune properties of breast milk are in women nursing children beyond two years. We don't know that the milk still contains antibodies. On the other hand, we don't know that it doesn't. Certainly up to the age of two years (where the studies stop), the breast milk continues to strengthen and augment and *prime* the child's own immune system. Seems to me I have references in my office also that talk about how breastfeeding *protects* children against botulism. One study showed that the breastfed babies who got botulism all survivied, while the bottle-fed babies who got botulism all died. Katherine A. Dettwyler, Ph.D. Associate Professor of Anthropology Specialist in infant feeding and growth of children Texas A&M University e-mail to [log in to unmask] (409) 845-5256 (409) 778-4513