Many members of the Flaviviridae family are emerging and reemerging human pathogens that have caused outbreaks of devastating and often fatal diseases and represent a serious public health problem on a global scale. There is no single attenuation strategy that exists which is sufficient to prepare a safe, efficacious and immunogenic live attenuated virus vaccine that will work universally for Flaviviridae. This patent application claims live attenuated flavivirus vaccines, live attenuated multivalent flavivirus vaccines, and methods of preventing flavivirus infections as well as methods of making the vaccines claimed in the application. More specifically, this patent application claims methods for attenuating a flavivirus or chimeric flavivirus using a synergistic dual strategy involving inserting miRNA-targeting sequences to restrict virus replication in target hosts, cells and/or tissues and placing one or more flavivirus genes under translational control of an internal ribosomal entry site (IRES).