A Journey From SARS-CoV-2 to COVID-19 and Beyond: A Comprehensive Insight of Epidemiology, Diagnosis, Pathogenesis, and Overview of the Progress into Its Therapeutic Management

Abstract

The 2019 novel coronavirus (2019-nCoV), commonly known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or coronavirus disease 2019 (COVID-19), was first revealed in late 2019 in Wuhan city, Hubei province, China. It was subsequently spread globally and thereby declared as a pandemic by WHO in March 2020. The disease causes severe acute respiratory illness and is highly contagious due to the fast-onward transmission. As of the mid of November 2020, the disease has affected 220 countries with more than 16 million active cases and 1.3 million deaths worldwide. Males, pregnant women, the elderly, immunosuppressed patients, and those with underlying medical conditions are more vulnerable to the disease than the general healthy population. Unfortunately, no definite treatment is available. Although remdesivir as an antiviral had been approved for use in those above 12 years of age and 40 kg weight group, it has been observed to be ineffective in large-scale SOLIDARITY trials by WHO. Moreover, dexamethasone has been found to increase the recovery rate of ventilated patients; oxygen and inhaled nitric oxide as a vasodilator have been given emergency expanded access. In addition, more than 57 clinical trials are being conducted for the development of the vaccines on various platforms. Two vaccines were found to be significantly promising in phase III results. It is concluded that till the approval of a specific treatment or development of a vaccine against this deadly disease, the preventive measures should be followed strictly to reduce the spread of the disease.

Keywords: COVID-19; SARS-CoV-2; azithromycin; coronavirus; dexamethasone; hydroxychloroquine; remdesivir; vaccines.

FIGURE 1

Schematic overview of SARS-CoV-2 epidemiology, pathogenesis and clinical features, diagnosis, management, and prevention [Figure created with BioRender, www.biorender.com].

FIGURE 2

Schematic diagram of SARS-CoV-2 virus structure and genome organization. (A) The viral surface proteins, spike (S), envelope (E), and membrane (M) are embedded in a lipid bilayer. The single-stranded positive-sense viral RNA is associated with the nucleocapsid (N) protein. Diagram was created with BioRender. (B) The genome organization of SARS-CoV-2 viral RNA, which is adapted from GenBank accession number: MN908947, is characterized by sequence alignment against two representative members of the betacoronavirus genus. The entire genome sequence is ∼30 kb long [reproduced with permission] (Lee et al., 2020b).

FIGURE 3

(A) Spike proteins on the surface of the coronavirus bind to angiotensin-converting enzyme 2 (ACE2) receptors on the surface of the target cell; (B) The type II transmembrane serine protease (TMPRSS2) binds to and cleaves the ACE2 receptor. In the process, the spike protein is activated; (C) cleaved ACE2 and activated spike protein facilitate viral entry. TMPRSS2 expression increases cellular uptake of the coronavirus (Lee et al., 2020).

FIGURE 4

The treatment and management option for COVID-19 patients [reproduced with permission] (Yang Y. et al., 2020).