This work was supported by a grant number of 990204-009 from Avicenna Research Institute. Footnotes Conflict of Interest The authors declare no competing interests regarding this article.. the same as the SARS-CoV spike one and is known as the Angiotensin-Converting Enzyme 2 (ACE2) 4. Virus attachment to the host cell, subsequent infection, antigen presenting and prevention of infection of the SARS CoV-2 is described in a simple schematic figure (Figure 1). Open in a separate window Figure 1. Schematic illustration of viral vector vaccines against SARS CoV-2 and prevention of infection. Intramuscular (IM), Electroporation (EP). Since the SARS-Cov-2 emerged and caused a Gilteritinib hemifumarate novel disease in 2019, scientists from all over the world have been on the research to overcome this pandemic. Many efforts in regard to COVID-19 vaccines started with the development of vaccines from various platforms against SARSCoV-2 infection. Different categories of the developing vaccine candidates are shown in figure 2. Most of them are based Sh3pxd2a on the protein subunit specially the S-protein of SARSCoV-2 5. Open in a separate window Figure 2. Different categories of SARS-CoV-2 Vaccines. Source: ClinicalTrials.gov website; WHO. These current vaccine candidates developed based on various platforms, including Inactivated Viral vaccines (IV), Live Attenuated Viral vaccines (LAV), peptide Gilteritinib hemifumarate or subunit based vaccines, Virus-Like Particles (VLP), replicating viral vector vaccines, on-replicating viral vector vaccines, and DNA or mRNA-based vaccines. Two classical vaccines such as LAV and IV vaccines have high potential to elicit a protective immune response, while some limitations are associated with an infection and LAV vaccines can revert to wild type 6. The aim of this study was to focus on the new platforms of the current vaccine candidates. New vaccine strategies based on recombinant DNA and peptide technology would have more safety and stability than the current vaccine strategies and would promise the manufacture and development of new generation of vaccines in a more predictable approach 6,7. Some of these new generation platforms of vaccines are introduced in this study and include peptide based, nucleic acid based (DNA or RNA), viral vector and artificial Antigen Presenting Cells (aAPC) based vaccines 6. Peptide based vaccines Peptide vaccines are designed based on a single or highly immunogenic small epitopes. Most of COVID-19 candidate vaccines were designed based on protein subunit specially using the SARS-CoV-2 spike protein (S protein) or part of it as the immunogenic antigen. The glycoprotein S consists of S1 and S2 subunits. The Receptor Binding Domain (RBD) of the S protein potentially attaches to the receptor (ACE2) of the host cell 8. The following vaccines based on peptide subunit are conducted in clinical phase III for the prevention of COVID-19 (the registration numbers are included in table 1): – The Full length recombinant SARS CoV-2 glycoprotein S vaccine adjuvanted with Matrix M – The Recombinant SARS-CoV-2 vaccine (CHO Cell) in which the RBD chemically conjugates to tetanus toxoid plus adjuvant) – The CIGB-66 vaccine based on RBD plus aluminium hydroxide adjuvant – EpiVacCorona vaccine in which short fragments of a viral spike protein are conjugated to a large carrier protein (has just been approved and no published article could be found). Table 1. Protein subunit vaccines, curent clinical phases compared to DNA vaccines 12. Table 2. Viral vector (non-replicating) vaccines, clinical trials. Source: ClinicalTrials.gov website; WHO aerosol, oral, intra dermal, and intramuscular routes. The aerosol route is considerably applicable when targeting a respiratory virus due to eliciting protective immune responses. It is also worth noting that viral vector vaccines tend to induce a robust response in both B cells and T cells 13 with a single dose and a good safety profile 10. Common to Gilteritinib hemifumarate some vaccines, adverse effects of viral vector vaccines include fever, pneumonia,.