In this review, we attempted to highlight the uniqueness and difference among vaccines. Vaccine is a biological preparation that improves immunity to diseases and protect us from Covid 19. The term vaccine applies to all biological preparations produced by the living organisms, that enhance immunity against disease and the techniques used for the development of vaccines were reverse vaccinology, structural vaccinology, synthetic biology, and vaccine adjuvants. Besides these mRNA vaccines, we will also highlight the Protein subunit vaccines, which include separated proteins from viral or bacterial diseases, vaccines improve the immune system's "memorization" of the pathogen by imitating a milder form of disease, might provide a viable alternative to the mRNA-based coronavirus vaccines and discuss their advantages and disadvantages over the mRNA-based vaccines.