Abstract
The sudden outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in late 2019 has necessitated discussions on different facets of the disease. These include its transmission, pathogenesis and vaccine development. The aims of this study were to discuss the SARS-COV-2 vaccines development, mechanisms of action as well as the general acceptance of these vaccines by various countries/or people. Sequel to the outbreak, several vaccines models have been discovered with promising outcomes. Few of these vaccines have been approved for emergency use; but so far, only a small portion of the world’s population has been vaccinated, which is a global problem that requires urgent intervention. Knowledge of the immune response associated with SARS-CoV-2 infection is imperative to the understanding of the mechanisms of action of these vaccines. Additional researches on some of these SARS-CoV-2 prominent vaccines have become necessary. The step-to-step development of these vaccines and their effectiveness will clear the air and increase the citizen's trust in these vaccines. Amid SARS-CoV-2 vaccine development; two DNA adenovirus vaccines were developed in the United States (Oxford-AstraZeneca and Johnson and Johnson). In addition, two other mRNA modified lipid nanoparticle vaccines were developed in Europe (Pfizer-BioNTech and Moderna). This review covered the discussion on the basic molecular mechanisms of these vaccines; with particular focus on the in vivo responses toward these vaccines recorded by the vaccinated individuals.
Highlights
Immunogenicity, the molecular response of a living system to antigenic epitopes presents in an invading infectious agent; is a critical component in vaccine development
The objectives of this review were to cover the detailed delivery systems adopted by the four different SARS-CoV-2 vaccines (i.e. Pfizer BioNTech, Moderna, Oxford-AstraZeneca, and Johnson and Johnson), their mechanisms of action, and how human systems respond to injection with such vaccines
The S2 protein binds to the host cell; activating the protein responsible for viral entry via conformational changes mediated by the cellular cathepsis L and the trans-membrane protease serine 2 (TMPRS2) (Cevik et al, 2020)
Summary
Immunogenicity, the molecular response of a living system (often mammalian) to antigenic epitopes presents in an invading infectious agent; is a critical component in vaccine development. Effective vaccine development depends on the ability of the antigen of interest to induce host immune response to produce antibodies that will regulate invasion of the body by the disease pathogens Certain viruses such as SARS CoV-2 can evade the host immune system; thereby causing further infection to the neighboring tissues. The mechanisms of action of the four SARS-CoV-2 vaccines discussed in this paper were based on knowledge of the human immunological response to SARS-CoV-2 infection (Pedro et al, 2020; Labeau et al, 2020; Azkur et al, 2020) The actions of these vaccines depend on the ability of the vaccine encoded antigen segment to induce immunity against the SARS-CoV-2 spike protein The objectives of this review were to cover the detailed delivery systems adopted by the four different SARS-CoV-2 vaccines (i.e. Pfizer BioNTech, Moderna, Oxford-AstraZeneca, and Johnson and Johnson), their mechanisms of action, and how human systems respond to injection with such vaccines
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