Replicating Viral Vector-Based Vaccines for COVID-19: Potential Avenue in Vaccination Arena

Abstract

The “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)” is the third member of human coronavirus (CoV) that is held accountable for the current “coronavirus disease 2019 (COVID-19)” pandemic. In the past two decades, the world has witnessed the emergence of two other similar CoVs, namely SARS-CoV in 2002 and MERS-CoV in 2013. The extent of spread of these earlier versions was relatively low in comparison to SARS-CoV-2. Despite having numerous reports inclined towards the zoonotic origin of the virus, one cannot simply sideline the fact that no animal originated CoV is thus far identified that is considered similar to the initial edition of SARS-CoV-2; however, under-sampling of the diverse variety of coronaviruses remains a concern. Vaccines are proved to be an effective tool for bringing the end to such a devastating pandemic. Many vaccine platforms are explored for the same but in this review paper, we will discuss the potential of replicating viral vectors as vaccine carriers for SARS-CoV-2.

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

“…Based on data review obtained during phase I, Phase II trials were conducted with larger cohorts as well as elderly age volunteers (18–85) with similar dose treatment of phase I. Also, the booster dose administration (prime-boost) was implemented when immunogenicity responses were inadequate ( Chavda et al, 2022 ).…”

“…In the phase 2b/3 trial (NCT04990466), IIBR partnered with the US-based NRx Pharmaceuticals (Cromos, Brilife, Georgia) to complete late-stage clinical studies and mass immunization of the Georgian population in the year 2021. A randomized, multi-center, and observer-blind study was conducted on 550 volunteers in the age group of 18–90 with two intramuscular (IM) injections of the IIBR-100 (prime-boost) or an active comparator at days 0 and 28 days, and followed up was performed to 12 months post last vaccination ( Chavda et al, 2022 ). NRx announced that this vaccine not only does induce a single dose of a vaccine protecting the volunteers from SARS-CoV-2 challenge but also induces adequate levels of neutralizing antibodies against the Omicron.…”

“…The results of phase I (ChiCTR2000037782) on 60 healthy subjects and phase II (chiCTR2000039715) on 720 healthy subjects clinical indicated that the vaccine is very tolerated and immunogenic in inducing extensive adaptive immune responses, especially at the generation of mucosal IgA, systemic IgG, and T cell responses. Based on promising results obtained during phase I and phase II clinical trials, the phase III trial (ChiCTR2100051391) was conducted in the Philippines involving 40,000 subjects ( Chavda et al, 2022 ). Phase III trial is under investigation, and no data has been reported on therapeutic efficacy, an adjuvant used, and treatment-related SAE.…”

Booster Dose for Tackling Emerging Variant of SARS-CoV-2

“…Initially, the pathogen was unidentified, and the disease was contemplated as "pneumonia of unknown etiology." Soon afterward, a novel coronavirus (CoV) family was associated with the etiology of the illness (2). The four primary coronavirus subdivisions are alpha, beta, gamma, and delta.…”

Therapeutics to Tackle Omicron Outbreak

“…A study of binding interactions, conducted by Lupala et al [19] using atomistic molecular dynamics simulations, revealed that binding of Omicron S-protein is stronger to the human ACE2 protein than the original strain. This might be attributed to changes at the ACE2-RBD junction that improved hydrophobic interactions and suppressed solvent-specific surface area [20,21]. Therefore, many of the approved monoclonal antibodies (mAbs) became ineffective or showed less activity against the Omicron variant.…”