Harnessing Nanocarriers to Advance Vaccine Development.

Nanocarriers (NCs) are nanosized delivery systems that can be engineered from lipids, polymers, inorganic compounds, viral structural proteins and extracellular vesicles to transport cargo efficiently. Their unique characteristics, including biocompatibility, a modifiable surface for targeted delivery, increased uptake and sustained release of antigens, make them an ideal platform for vaccine development. NCs can also improve antigen stability, increase retention and act as adjuvants to enhance immune responses. Nanovaccines offer promising solutions to overcome the issues of conventional vaccine design in terms of efficacy, time and resource consumption. However, challenges in developing nanovaccines, such as a limited understanding of NC mechanisms of action, upscaling, safety and regulatory issues, need to be addressed to advance NCs into licensed vaccines. This review describes the types, advantages, limitations and clinical applications of NCs, with updates on nanovaccine candidates for infectious diseases and cancer in clinical trials, along with key lessons learnt. The development of nanovaccines that are protective against multiple pathogenic strains or for prophylactic treatment for cancer could potentially enhance global capacity in pandemic preparedness and disease prevention. Hence, continued research to advance NC technologies and to gain a deeper understanding of their mechanisms of immune activation is warranted to pave the way for more effective, personalized and accessible vaccines.