Table 1.

Comparison of different vaccines against COVID-19. This chart details the exposure method, required doses, technological overview, and manufacturers of current COVID-19 vaccines.

Company	Required Doses	Technological and Dosage Overview
Exposure method: RNA (mRNA)
Pfizer & BioNTech		The Pfizer BioNTech vaccine dosage is 0.3 mL and requires 2 doses, 21 days apart and the Moderna vaccine dosage is 0.5 mL and requires 2 doses, 20 days apart [133,134].Lipid nanoparticles encapsulate mRNA, allowing for the precise delivery of the genetic components of the vaccine, optimizing the translation of the proteins [135].
Moderna
Exposure method: Viral Vector
Sputnik V (recombinant adenovirus type 26 and 5)		The SputnikV vaccine dosage is 0.5 mL with 2 vaccine doses, 21 days apart [136]. The Johnson & Johnson vaccine dosage is 0.5 mL and requires 1 vaccine dose [137]. The Oxford AstraZeneca vaccine dosage is 0.5 mL with 2 vaccine doses, 8–12 weeks apart [138].Utilizes an adenovirus vector to elicit spike proteins on cell surfaces resulting in immune responses through the activation of antibodies [75].
Johnson & Johnson (recombinant adenovirus type 26 vector)
Oxford AstraZeneca (adenovirus)
Exposure method: Protein based
Novavax		Utilizes the S protein from SARS-CoV-2 with recombinant protein nanoparticles and adjuvant MatrixM to elicit desired immune responses, and requires 2 vaccine doses, 21 days apart [139].
Zifivax		The vaccine is composed of antigens and viral particles of SARS-CoV-2 that will generate an immune response and requires 3 vaccine doses, 0.5 mL each, over the course of 2 months [140,141].
Exposure method: Peptide-antigen based
EpiVacCorona		Three peptide antigens for SARS-CoV-2 are synthesized consisting of the spike protein and a chimeric protein, an aluminum hydroxide adjuvant is utilized to synthesize the vaccine, and requires 2 vaccine doses, 0.5 mL each, over the course of 21–28 days [142].
Exposure Method: Inactivated Virus
WIBP-CorV Sinopharm		Inactive whole virus technology has been widely studied and is effective for individuals with impaired immune systems and requires 2 vaccine doses, 0.5 mL each, with an interval of 3–4 weeks [132,143].
BBIBP-CorV Sinopharm		Inactive whole virus technology has been widely studied and is effective for individuals with impaired immune systems and requires 2 vaccine doses, 0.5 mL each, with an interval of 3–4 weeks [132,143].