World Small Animal Veterinary Association, World Congress- Vancouver 2001 snippet: MLV vaccines generally produce longer duration, more solid immunity. Both humoral and cell-mediated immune systems participate strongly in the response. A single vaccination may provide significant immunologic memory (as long as there is no maternal AB interference). snippet: The recommendation for annual revaccination is a practice that was officially started in 1978. This recommendation was made without any scientific validation of the need to booster immunity so frequently. In fact, the presence of good humoral antibody levels blocks the anamnestic response to vaccine boosters just as maternal antibody blocks the response in some young animals. http://www.vin.com/VINDBPub/SearchPB/Proceedings/PR05000/PR00141.htm ~Amy~ [Posted in FML issue 4645]