COVID-19 Vaccines: Current Conditions and Future Prospects

Abstract

It has been over a year since SARS-CoV-2 was first reported in December of 2019 in Wuhan, China. To curb the spread of the virus, many therapies and cures have been tested and developed, most notably mRNA and DNA vaccines. Federal health agencies (CDC, FDA) have approved emergency usage of these S gene-based vaccines with the intention of minimizing any further loss of lives and infections. It is crucial to assess which vaccines are the most efficacious by examining their effects on the immune system, and by providing considerations for new technological vaccine strategies in the future. This paper provides an overview of the current SARS-CoV-2 vaccines with their mechanisms of action, current technologies utilized in manufacturing of the vaccines, and limitations in this new field with emerging data. Although the most popular COVID-19 vaccines have been proven effective, time will be the main factor in dictating which vaccine will be able to best address mutations and future infection.

Keywords: COVID-19; adenovirus; angiotensin-converting enzyme 2 (ACE2); lipid nanoparticles; mRNA vaccine; spike protein.

Figure 1

COVID-19 Infection and Transmission. (A): Illustration of SARS-CoV-2. (B): The potential mechanisms of infection for SARS-CoV-2, which preferentially infects respiratory tract cells. (C): COVID-19 transmission when an infected individual is in close contact with others, spreading via droplets from talking, breathing, coughing, or sneezing.

Figure 2

Mechanism for lipid nanoparticles in mRNA Vaccine and activation of immune cells and immune response. (A): This figure illustrates the mechanisms for the interaction between the lipid nanoparticles containing the spike mRNA, as well as mRNA release once in the body. (B): This figure illustrates the immune responses elicited once the mRNA spike proteins have entered the body, through the expressions of CD4+ and CD8+ T cells and B cells. (C): This figure details the infection of SARS-CoV-2 with the binding of the spike protein to the ACE2 receptor, ACE2 and co-receptor, and novel receptors to account for the potential methods of viral entry, and the neutralizing effects of B and T cell interactions after vaccination.