New vaccines derived from BCG
There are several candidate live vaccines in development. Most are based on BCG. These strains differ from the parent BCG in that they may now over-express a particular antigen or may now produce a specific cytokine. Such changes are thought to improve the immune response. This improvement remains to be demonstrated. However, the differences in BCG produced in various laboratories could make it difficult to define requirements for such novel TB vaccines. For example, it may be possible to show that a novel vaccine derived from BCG (Copenhagen) can result in an improved immune response. Further testing may be necessary to show that the "improved" BCG is "better" than, for example, BCG (Montreal) or BCG (Paris).