Viral vector and nucleic acid vaccines against COVID-19: A narrative review

Abstract

After about 2 years since the first detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Wuhan, China, in December 2019 that resulted in a worldwide pandemic, 6.2 million deaths have been recorded. As a result, there is an urgent need for the development of a safe and effective vaccine for coronavirus disease 2019 (COVID-19). Endeavors for the production of effective vaccines inexhaustibly are continuing. At present according to the World Health Organization (WHO) COVID-19 vaccine tracker and landscape, 153 vaccine candidates are developing in the clinical phase all over the world. Some new and exciting platforms are nucleic acid-based vaccines such as Pfizer Biontech and Moderna vaccines consisting of a messenger RNA (mRNA) encoding a viral spike protein in host cells. Another novel vaccine platform is viral vector vaccine candidates that could be replicating or nonreplicating. These types of vaccines that have a harmless viral vector like adenovirus contain a genome encoding the spike protein of SARS-CoV-2, which induces significant immune responses. This technology of vaccine manufacturing has previously been used in many human clinical trials conducted for adenoviral vector-based vaccines against different infectious agents, including Ebola virus, Zika virus, HIV, and malaria. In this paper, we have a review of nucleic acid-based vaccines that are passing their phase 3 and 4 clinical trials and discuss their efficiency and adverse effects.

Extracellular Vesicle-Based SARS-CoV-2 Vaccine

“…Nonetheless, booster vaccination is recommended, as the protective effect diminishes over time. While many COVID-19 vaccines are being developed around the world, at present, the main vaccines are mRNA- and viral vector-based vaccines [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 ]. Vaccine development is progressing using various methods, including conventional inactivated and recombinant protein vaccines.…”

“…The components of pathogens used in previous inactivated vaccines were mainly proteins and polysaccharides, whereas the COVID-19 vaccine (Pfizer and Moderna) used mRNA. Genetic vaccines, such as mRNA vaccines and viral vector vaccines, have the advantage of being put into practical use quickly, and are useful in pandemic scenarios requiring urgency [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 ]. mRNA vaccines using the S protein present on the surface of SARS-CoV-2 have been developed and have shown promising results.…”

The Significance of Digitalisation and Artificial Intelligence in The Healthcare Sector: A Review

“…As a result, it was able to reach somewhat sufficient stages. For example, what occurred at the end of 20219 with the spread of the COVID-19 pandemic and the death of many people, artificial intelligence was able to control the spread of the virus, track cases of infection and analyse patient data with high speed and accuracy [51][52][53][54][55]. So, without artificial intelligence, the health sector is not working properly.…”

Co‐delivery of a trimeric spike DNA and protein vaccine with aluminum hydroxide enhanced Th1‐dominant humoral and cellular immunity against SARS‐CoV‐2

“…6 In addition, DNA vaccines have more benefits than mRNA vaccines; DNA vaccines do not require the extra step of in vitro transcription or require ultralow temperature storage, which limits global transportation of mRNA vaccines. 7 However, a hurdle for DNA vaccines is the limited amount of antigen production, which causes low immunogenicity with poor antigen-specific antibody responses. 8 To ensure the efficacy of DNA vaccines, electric pulses, [9][10][11] or gene guns 12,13 are commonly used to facilitate plasmid DNA delivery into the nucleus of host cells for encoded protein expression.…”

“…CD8 + T cells also play an important role in inducing cross‐protective immune responses against SARS‐CoV‐2 variants 6 . In addition, DNA vaccines have more benefits than mRNA vaccines; DNA vaccines do not require the extra step of in vitro transcription or require ultralow temperature storage, which limits global transportation of mRNA vaccines 7 …”