Emerging Variants of SARS-CoV-2 and Novel Therapeutics Against Coronavirus (COVID-19)

Excerpt

Coronavirus disease 2019 (COVID-19), the illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has had a devastating effect on the world's population resulting in more than 6 million deaths worldwide and emerging as the most significant global health crisis since the influenza pandemic of 1918. Since being declared a global pandemic by the World Health Organization (WHO) on 11 March 2020, the virus continues to cause devastation, with many countries continuing to endure multiple waves of outbreaks of this viral illness.

Adaptive mutations in the viral genome can alter the virus's pathogenic potential. Even a single amino acid exchange can drastically affect a virus's ability to evade the immune system and complicate the vaccine development progress against the virus. SARS-CoV-2, like other RNA viruses, is prone to genetic evolution while adapting to their new human hosts with the development of mutations over time, resulting in the emergence of multiple variants that may have different characteristics compared to its ancestral strains. Periodic genomic sequencing of viral samples helps detect new genetic variants of SARS-CoV-2 circulating in communities, especially in a global pandemic. The genetic evolution of SARS-CoV-2 was minimal during the early phase of the pandemic, with the emergence of a globally dominant variant called D614G, which was associated with higher transmissibility but without increased disease severity of its ancestral strain. Another variant was identified in humans, attributed to transmission from infected farmed mink in Denmark, which was not associated with increased transmissibility.

Since then, multiple variants of SARS-CoV-2 have been described, of which a few are considered variants of concern (VOCs), given their impact on public health. VOCs are associated with enhanced transmissibility or virulence, reduction in neutralization by antibodies obtained through natural infection or vaccination, the ability to evade detection, or a decrease in therapeutics or vaccination effectiveness. Based on the epidemiological update by the WHO, as of 11 December 2021, five SARS-CoV-2 VOCs have been identified since the beginning of the pandemic: