Vaccine Adjuvants and Delivery Systems: A Comprehensive Review

Vaccination stands as the primary tool for preventing diseases and is considered one of the most cost-effective public health measures available. Immunization through vaccination serves as our best defense against serious and sometimes fatal infectious diseases. Adjuvants play a crucial role in increasing vaccination efficacy. While aluminum salts have historically been the most common adjuvants, recent research has turned to new compounds with enhanced adjuvant properties and improved safety. Cutting-edge nanotechnology, utilizing nanoformulations and novel delivery systems, has enhanced efficacy and reduced adverse effects. Microparticles, emulsions, and immunostimulants have become key targets due to their vast potential in vaccine production. Additionally, advanced drug delivery systems (DDS) have been developed using sophisticated technology to expedite and optimize the delivery of drugs and vaccines to specific target sites, maximizing therapeutic efficacy and minimizing drug accumulation in the body. The latest DDSs offer numerous advantages over conventional drug delivery systems, including heightened performance, precision, and efficiency. Comprising nanomaterials or miniaturized devices, these DDSs boast multifunctional components that are biocompatible, biodegradable, and possess high viscoelasticity, resulting in an extended circulating half-life. This review aims to provide an elaborate and current overview of adjuvants and the technological advancements in vaccine delivery systems.