The structural design, preparative methods and chemical composition of two structural formulations of bivalent vaccines against morphine-heroin addiction (morphine-6-hemisuccinyl-EDC-TFCS-tetanus toxoid and 3-O-carboxymethylmorphine-EDC-TFCS-tetanus toxoid), are disclosed. These vaccines are suitable for human use in which they are capable of triggering the synthesis of polyclonal antibodies against morphine opiate and its structural analogue, heroin, through the repeated in vivo administration of these formulations, in active vaccination protocols, in pre-clinical studies in rodents. The active vaccination paradigm through which these immunogens trigger a humoral immune response consolidated with a long-term immunological memory, characterized by the presence of high titers of specific antibodies against these two drugs of abuse, is also disclosed. Furthermore, the present invention reveals the efficacy of these conjugate formulations for triggering a sustained immunoprotection against morphine and heroin addiction using an intravenous self-administration paradigm of these two opiate substances in the rodent. Finally, a discussion is also made on the potential future use of these immunoconjugates in active vaccination protocols for treating both morphine and heroin addiction in the humans.