COVID-19 Pandemic and Vaccines Update on Challenges and Resolutions

Abstract

The coronavirus disease (COVID-19) is caused by a positive-stranded RNA virus called severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), belonging to the Coronaviridae family. This virus originated in Wuhan City, China, and became the cause of a multiwave pandemic that has killed 3.46 million people worldwide as of May 22, 2021. The havoc intensified with the emergence of SARS-CoV-2 variants (B.1.1.7; Alpha, B.1.351; Beta, P.1; Gamma, B.1.617; Delta, B.1.617.2; Delta-plus, B.1.525; Eta, and B.1.429; Epsilon etc.) due to mutations generated during replication. More variants may emerge to cause additional pandemic waves. The most promising approach for combating viruses and their emerging variants lies in prophylactic vaccines. Several vaccine candidates are being developed using various platforms, including nucleic acids, live attenuated virus, inactivated virus, viral vectors, and protein-based subunit vaccines. In this unprecedented time, 12 vaccines against SARS-CoV-2 have been phased in following WHO approval, 184 are in the preclinical stage, and 100 are in the clinical development process. Many of them are directed to elicit neutralizing antibodies against the viral spike protein (S) to inhibit viral entry through the ACE-2 receptor of host cells. Inactivated vaccines, to the contrary, provide a wide range of viral antigens for immune activation. Being an intracellular pathogen, the cytotoxic CD8+ T Cell (CTL) response remains crucial for all viruses, including SARS-CoV-2, and needs to be explored in detail. In this review, we try to describe and compare approved vaccines against SARS-CoV-2 that are currently being distributed either after phase III clinical trials or for emergency use. We discuss immune responses induced by various candidate vaccine formulations; their benefits, potential limitations, and effectiveness against variants; future challenges, such as antibody-dependent enhancement (ADE); and vaccine safety issues and their possible resolutions. Most of the current vaccines developed against SARS-CoV-2 are showing either promising or compromised efficacy against new variants. Multiple antigen-based vaccines (multivariant vaccines) should be developed on different platforms to tackle future variants. Alternatively, recombinant BCG, containing SARS-CoV-2 multiple antigens, as a live attenuated vaccine should be explored for long-term protection. Irrespective of their efficacy, all vaccines are efficient in providing protection from disease severity. We must insist on vaccine compliance for all age groups and work on vaccine hesitancy globally to achieve herd immunity and, eventually, to curb this pandemic.

Immunogenicity of ChAdOx1 nCoV-19 vaccine after a two-dose inactivated SARS-CoV-2 vaccination of dialysis patients and kidney transplant recipients

“…Therefore, a preventive strategy is recommended to prepare for potentially aggressive disease. Immunogenicity of vaccine platforms and individual immune status are variable 5 . When whole, inactivated SARS-CoV-2 virus was utilized as a vaccine nationwide, optimal immune responses were observed among immunocompetent individuals 6 .…”

Branches of a Rotten Tree - Trending Variants of COVID-19 and their Oral Manifestations

“…As a result, collaboration among numerous institutions, researchers, governments, and pharmaceutical firms is unavoidable if the present COVID-19 epidemic and future outbreaks are to be avoided [21]. Because of the pandemic's worldwide scope, multiple international regulatory and scientific authorities have collaborated to develop and exchange important safety and effectiveness data for innovative vaccines [22][23][24][25][26][27][28][29][30][31]. The counteraction and treatment of this profoundly infectious respiratory infection need a multidisciplinary and interprofessional procedure including doctors from numerous specialities, attendants, drug specialists, general wellbeing trained professionals, and government authorities [1].…”

Heat Treatment Promotes Ubiquitin-Mediated Proteolysis of SARS-CoV-2 RNA Polymerase and Decreases Viral Load

“…Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the culprit of the coronavirus disease 2019 (COVID-19) pandemic, is highly contagious and transmissible among humans [ 1 ]. The virus invades cells through interaction of its spike protein with the cell membrane protein angiotensin-converting enzyme 2 (ACE2) [ 1 ].…”

“…Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the culprit of the coronavirus disease 2019 (COVID-19) pandemic, is highly contagious and transmissible among humans [ 1 ]. The virus invades cells through interaction of its spike protein with the cell membrane protein angiotensin-converting enzyme 2 (ACE2) [ 1 ]. Although prophylactic/therapeutic vaccines were rapidly developed and widely applied to curb the virus spread, several SARS-CoV-2 variants (e.g., delta, delta plus, omicron (B.1.1.529), and IHU) have been suggested or reported to lead to partial or even complete escape from immune protection provided by vaccination [ 1 – 3 ].…”