A review of epidemiology, clinical features and disease course, transmission dynamics, and neutralization efficacy of SARS-CoV-2 variants

Abstract

After the first detection in November 2019, SARS-CoV-2 has spread rapidly over the continents and started the pandemic of the millennium. In addition to several novels and repurposed monoclonal antibodies (mAbs) as a therapeutic option against COVID-19, scientists from across the world have developed several candidate vaccines, developed mainly targeting the Wuhan strain, with very promising results to combat this pandemic. Unfortunately like any RNA viruses, SARS CoV-2 has also gone through the accumulation of hundreds and thousands of mutations in their genome lead to the development of several variants of concerns (VOC) and variants of interests (VOI), resulting in increased transmissibility and virulence of the virus, along with their capacity to escape cross-protection. Seemingly, the main hindrance of containing this pandemic right now is the effectiveness of currently available vaccines and mAbs against newly emerging variants. Therefore, it is important to monitor variants epidemiology, transmission dynamics, clinical characteristics, as well as their immune evasion capacity to implement appropriate vaccine strategy and other containment measures. In this review, we tried to focus on variants characteristics and to what extent they can escape immunity, provided by both available vaccinated sera and convalescent sera. A stringent literature review was performed using various databases, mentioned in the methodology portion. The current geographical distribution of these variants of SARS CoV-2 has been presented using a heat map. Findings from published articles comparing these variants, in terms of genome epidemiology, transmissibility, viral load dynamics, and association with different waves have been described briefly. Due strength was given while describing variants neutralization potency against current vaccines, mAbs, and also against convalescent sera. Data from both clinical trials and in vitro/ex-vivo studies have been discussed here. Comparative findings from several articles were brought into one concise paper. After careful reviewing of all the available data, it was clear that, without hesitation, we should strengthen our vaccination strategy, because the severity of COVID 19 is reasonably lower, irrespective of variants and vaccine used. We hope that many falsified myths and beliefs regarding vaccine immunity and emerging variants will be clarified in light of this available evidence, which we summarized in our paper.