Strategies for Vaccination: Conventional Vaccine Approaches Versus New-Generation Strategies in Combination with Adjuvants

Abstract

The current COVID-19 pandemic, caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), has raised significant economic, social, and psychological concerns. The rapid spread of the virus, coupled with the absence of vaccines and antiviral treatments for SARS-CoV-2, has galvanized a major global endeavor to develop effective vaccines. Within a matter of just a few months of the initial outbreak, research teams worldwide, adopting a range of different strategies, embarked on a quest to develop effective vaccine that could be effectively used to suppress this virulent pathogen. In this review, we describe conventional approaches to vaccine development, including strategies employing proteins, peptides, and attenuated or inactivated pathogens in combination with adjuvants (including genetic adjuvants). We also present details of the novel strategies that were adopted by different research groups to successfully transfer recombinantly expressed antigens while using viral vectors (adenoviral and retroviral) and non-viral delivery systems, and how recently developed methods have been applied in order to produce vaccines that are based on mRNA, self-amplifying RNA (saRNA), and trans-amplifying RNA (taRNA). Moreover, we discuss the methods that are being used to enhance mRNA stability and protein production, the advantages and disadvantages of different methods, and the challenges that are encountered during the development of effective vaccines.

A Systematic Review on COVID-19 Vaccine Strategies, Their Effectiveness, and Issues

“…Moreover, adjuvants can be added to the interior of the lipid nanoparticles for further upregulation of the immune system's response to the vaccine. Lipid nanoparticle-based technology can be a beneficial solution to challenge RNA delivery to cells [149][150][151][152][153][154][155][156]. Vaccine development by nanotechnology improves nucleic acid delivery and conformationstabilized subunit vaccines to lymph nodes.…”

A two-dose optimum for recombinant S1 protein-based COVID-19 vaccination

“…Aluminum adjuvant was first used in clinical trials in the 1930s and is still used in approximately 80% of the vaccines that are delivered with adjuvants ( Bouazzaoui et al, 2021 ). Recently, it was reported that three doses of a dimeric RBD-based protein subunit vaccine adjuvanted with aluminum hydroxide were well-tolerated and immunogenic against COVID-19 in phase 1 and 2 trials ( Yang et al, 2021 ).…”

Linarin, a Glycosylated Flavonoid, with Potential Therapeutic Attributes: A Comprehensive Review

“…Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is a RNA airborne virus infection known as the pathogen responsible for coronavirus disease 2019 (COVID-19) [119]. Millions of COVID-19 patients have been reported thus far; however, there is no concrete evidence on the effectiveness and safety of the specific treatment against SARS-CoV-2 [120,121].…”