MRNA solves, no impact

Generally, all vaccines work through these three steps: Firstly, antigens and used adjuvants will be uptake by immune cells or other cells depending on the route of administration. Secondly, specified antigen-presenting cells (APCs) will be matured, and the vaccine antigens will be processed. Finally, specific B and T lymphocyte cells will be produced, and a proper immune response will be established. APCs, including dendritic cells, macrophages, and B cells, can take up the vaccine’s antigens and process the antigens into peptides suitable for expressing major histocompatibility molecules (MHCs) I or II.17 Naïve T cells interact with APCs MHC, recognize the vaccine antigen epitopes and are primed into either cytotoxic or helper T cells. In addition, B cells also will be activated through interaction with soluble or surface antigens by their receptors (BCR) and differentiated into plasma or memory B cells for the production of antigenspecific antibodies.4 The first step of vaccine development is designing of vaccine regarding the chosen platform (e.g., subunit, viral vector, mRNA, etc.). New designing methods and tools have made significant advances in the rational designing of vaccines due to an accumulated understanding of the biological and immunological mechanisms of immunity and technological understandings in the last few decades.18 The mode of action and immunological interaction between the immune system and the vaccine could be used initially to understand their efficacy, safety, and expected benefit for the vaccinated individual. In addition, different bioinformatics tools,19 and immunological databases, will be beneficial and, most times, essential for designing vaccines.20 Choosing a particular vaccine platform can depend on several factors, such as the level of expected protection, the mode of action, the characteristics of the pathogen, or the disease elimination strategy and time.21,22 Traditional and more established methods, including subunit vaccines, need more time to develop. However, most traditional platforms have been tested in different large populations for many years, and their advantages and disadvantages are well known.23 Also, designing tools for these platforms are well-developed and accessible. In contrast, regarding the limitations of traditional platforms (discussed later), if time is a critical factor, for example, when an infection is spreading rapidly and is becoming an epidemic and pandemic situation, there is an urgent need for rapid vaccine development.24 In addition, when a biological attack or bioterrorism has occurred with infections, R & D teams should turn to methods with decreased designing time, such as third-generation DNA and mRNA vaccines.25,26 These vaccines have many advantages in design and production over traditional vaccines, which were proven in the 2020 pandemic COVID-19.27,28 Although there are many challenges and unknowns in using new vaccine platforms, in emergency conditions such as the recent pandemic and unexpected biological attacks, the priority is the rapid design and production of a vaccine and vaccination to savelives.29