Combined Therapeutics (CTx) has developed an engineered mRNA vaccine platform capable of restricting antigen expression to targeted tissues. CTx has accomplished this restricted biodistribution by employing its proprietary MOP (multi-organ protection) system that engineers micro RNA binding sites (miRNAbs) into the 3’ UTR of the mRNA. These engineered miRNAbs enable differential antigen expression in different cells depending on the presence or absence of the homologous miRNA. In this way, leveraging knowledge of differential cell-specific miRNA expression levels allows the CTx mRNA platform to be engineered for specific targeted antigen expression. In the current vaccine application, CTx has engineered its mRNA-MOP vaccine platform to allow antigen expression at the injection site but inhibits broader systemic antigen expression.