Abstract
The development of DDS technology has contributed critically to the unprecedentedly rapid requirement for vaccines against COVID-19. LNP-based mRNA vaccines represent a subset of emerging DDS technology. Despite the groundbreaking nature of these vaccines, they are yet to be perfected and as such, new technologies are being developed to optimize these vaccines. This review will focus on exploring one of the modalities of recombinant protein vaccines and will introduce various findings on the enhancement of vaccine efficacy using antigen modification technologies, including VLPs and Fc-fusion proteins, and adjuvant improvements.