Vaccinations are the administration of antigenic materials to produce immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by a pathogen. Vaccinations are considered to be the most effective and cost-effective method of preventing infectious diseases. This book presents current research on vaccinations to treat a variety of diseases including cancer, bacterial meningitis, multiple sclerosis, hepatitis B, and tuberculosis. This book also presents a comparative study about vaccination behavior in health care students from different countries. Also presented is research on vaccinations for aqua cultured fish in order to control viral diseases.