Immune Response to SARS-CoV-2 Vaccines

Abstract

COVID-19 vaccines have been developed to confer immunity against the SARS-CoV-2 infection. Prior to the pandemic of COVID-19 which started in March 2020, there was a well-established understanding about the structure and pathogenesis of previously known Coronaviruses from the SARS and MERS outbreaks. In addition to this, vaccines for various Coronaviruses were available for veterinary use. This knowledge supported the creation of various vaccine platforms for SARS-CoV-2. Before COVID-19 there are no reports of a vaccine being developed in under a year and no vaccine for preventing coronavirus infection in humans had ever been developed. Approximately nine different technologies are being researched and developed at various levels in order to design an effective COVID-19 vaccine. As the spike protein of SARS-CoV-2 is responsible for generating substantial adaptive immune response, mostly all the vaccine candidates have been targeting the whole spike protein or epitopes of spike protein as a vaccine candidate. In this review, we have compiled the immune response to SARS-CoV-2 infection and followed by the mechanism of action of various vaccine platforms such as mRNA vaccines, Adenoviral vectored vaccine, inactivated virus vaccines and subunit vaccines in the market. In the end we have also summarized the various adjuvants used in the COVID-19 vaccine formulation.

Preliminary In Vivo Evidence of Oral Selenium Supplementation as a Potentiating Agent on a Vector-Based COVID-19 Vaccine in BALB/c Mice

“…It is possible to measure the protective effectiveness of antibodies and the success of humoral immune responses following vaccination by measuring the titers of SARS-CoV-2 anti-spike IgG antibodies [ 34 ]. Janssen vaccine has showed 72% efficacy in the USA, 66% efficacy in Latin America, and 57% documented efficacy in South Africa [ 35 ]. The same study also showed that the efficacy of Janssen vaccine can be boosted to 77% efficacy 14 days post-immunization and 85% after 28 days.…”

Impact of Treatment with Anti-CD20 Monoclonal Antibody on the Production of Neutralizing Antibody Against Anti–SARS-CoV-2 Vaccination in Mature B-Cell Neoplasms

“… 1 , 2 Once the mRNA vaccine encapsulated in lipid nanoparticles is taken up by human cells, such as dendritic cells or myocytes, it is translated into a viral spike protein antigen that stimulates B cells to produce a neutralizing antibody (nAb) against the spike protein, which prevents viral infection and also induces cytotoxic T cells that acquire the ability of cellular immune responses against infected cells. 3 , 4 Therefore, immunocompromised patients and patients receiving treatment with an immunosuppressive moiety are generally at high risk for impaired antibody response against anti–SARS-CoV-2 vaccination. 5 , 6 Among the various settings of immunosuppressive treatment, therapeutic approaches that deplete B cells or impair B-cell function, such as an anti-CD20 monoclonal antibody (MoAb) or inhibitors for B-cell receptor signaling, have especially attracted attention as risk factors for severe COVID-19 in patients with B-cell malignancies, including B-cell lymphomas (BCLs) and chronic lymphocytic leukemia.…”

Immunogenicity and Protective Efficacy of a SARS-CoV-2 mRNA Vaccine Encoding Secreted Non-Stabilized Spike Protein in Mice

“…The spike (S) protein of the virus, which contains the major neutralizing epitopes in the receptor binding domain (RBD) and N-terminal domain (NTD), has proved to be the most promising immunogen (18). Thus, most of the recently approved vaccines employ full-length S (with or without modification) or whole virus (inactivated) as a target antigen (19). titers 100TCID50 for the micro-VNT50 assay.…”