COVID-19 and SARS-CoV-2 Variants: Current Challenges and Health Concern

Abstract

The ongoing coronavirus disease 2019 (COVID-19) outbreak in Wuhan, China, was triggered and unfolded quickly throughout the globe by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The new virus, transmitted primarily through inhalation or contact with infected droplets, seems very contagious and pathogenic, with an incubation period varying from 2 to 14 days. The epidemic is an ongoing public health problem that challenges the present global health system. A worldwide social and economic stress has been observed. The transitional source of origin and its transport to humans is unknown, but speedy human transportation has been accepted extensively. The typical clinical symptoms of COVID-19 are almost like colds. With case fatality rates varying from 2 to 3 percent, a small number of patients may experience serious health problems or even die. To date, there is a limited number of antiviral agents or vaccines for the treatment of COVID-19. The occurrence and pathogenicity of COVID-19 infection are outlined and comparatively analyzed, given the outbreak's urgency. The recent developments in diagnostics, treatment, and marketed vaccine are discussed to deal with this viral outbreak. Now the scientist is concerned about the appearance of several variants over the globe and the efficacy of the vaccine against these variants. There is a need for consistent monitoring of the virus epidemiology and surveillance of the ongoing variant and related disease severity.

Keywords: COVID-19; SARS-CoV-2 variant; therapeutics; vaccine efficacy; wave of infection.

FIGURE 1

(A) Genomic organization of SARS-CoV-2: 5′ and 3′ terminal sequences of the genome of SARS-CoV-2. 5′-replicase ORF1ab-spike (S)-envelope (E)-matrix (M)-nucleocapsid (N)-3′ is the gene order. At the expected position shown in the figure, Nsp1, Nsp2, Nsp3, Nsp4, Nsp5, Nsp6, Nsp7, Nsp8, Nsp9, Nsp10, Nsp11, Nsp12, Nsp13, Nsp14, Nsp15, Nsp16, S, E, M, N serve as various ORF genes in the frame. (B) Structure of SARS CoV-2:The genomic size of β-coronavirus ranges from 29 to 32 Kb. The virion has a genomic RNA and phosphorylated nucleocapsid (N) protein with a nucleocapsid that is concealed within phospholipid bilayers and coated with the spike glycoprotein trimmer (S). In the envelope of the virus, the matrix (M) protein hemagglutinin-esterase (HE) and envelope (E) protein are placed amid S proteins.

FIGURE 2

The worldwide distribution of circulating SARS-CoV-2 lineages, (A) B.1.1.7, (B) B.1.351, (C) P.1, (D) B.1.429 + B.1.427, (E) B.1.525 on a time scale for South America, Europe United Kingdom, Oceania, North America, Global, Asia, Africa, and Europe-noUK. Source: https://www.gisaid.org/hcov19-variants/for the most recent global SARS-CoV-2 variant as of April 2021.