Viruses, Serums, Toxins, and Analogous Products; Marek's Disease Vaccines

We are amending the standard requirements for Marek's disease vaccines by including vaccines prepared from any of the three Marek's disease virus serotypes, and by defining the identity, safety, and efficacy requirements for vaccines prepared from each serotype or combinations of serotypes. We are also amending the requirements for labeling Marek's disease vaccines. These amendments are necessary based on the evolution of virus serotypes in the field, advances in the development of vaccines that are currently prepared to prevent the disease, and advances in the methods for evaluating such vaccines. The effect of this rule will be to save license applicants time by clarifying and codifying the guidelines developed for licensing these products over the past several years.