From single-dose vaccine delivery systems to nanovaccines

The application of micro- and nanotechnologies to the development of vaccine delivery systems started in the 70s. From that time onwards, significant advances in this field have opened up opportunities in the research of new adjuvants and the design of safer and more effective vaccines. The versatility of vaccine delivery vehicles represents an important feature in vaccine development. Indeed, the modulation of the composition, particle size and/or surface properties, offers a wide range of possibilities for overcoming natural barriers and controlling antigen release. Thus, it is currently accepted that besides their ability to enhance the low immunogenicity of new subunit and DNA vaccines, these delivery carriers represent a promising strategy for needle-free and single-dose vaccination. In this review article we aim to present the historical advances made in the field of vaccine delivery, particularly the progress made in the last two decades, describing our specific contribution, ranging from the idea of single-dose vaccination to the current concept of nanovaccines. Overall, this review illustrates the potential of nanosciences and nanotechnologies to solve the current problems of vaccination and, thus, to expand the immunization coverage worldwide.