SARS-CoV-2 Variants of Concern

Abstract

Since the COVID-19 pandemic first began in December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has continuously evolved with many variants emerging across the world. These variants are categorized as the variant of interest (VOI), variant of concern (VOC), and variant under monitoring (VUM). As of September 15, 2021, there are four SARS-CoV-2 lineages designated as the VOC (alpha, beta, gamma, and delta variants). VOCs have increased transmissibility compared to the original virus, and have the potential for increasing disease severity. In addition, VOCs exhibit decreased susceptibility to vaccine-induced and infection-induced immune responses, and thus possess the ability to reinfect previously infected and recovered individuals. Given their ability to evade immune responses, VOC are less susceptible to monoclonal antibody treatments. VOCs can also impact the effectiveness of mRNA and adenovirus vector vaccines, although the currently authorized COVID-19 vaccines are still effective in preventing infection and severe disease. Current measures to reduce transmission as well as efforts to monitor and understand the impact of variants should be continued. Here, we review the molecular features, epidemiology, impact on transmissibility, disease severity, and vaccine effectiveness of VOCs.

The Potential Role of Cytokine Storm Pathway in the Clinical Course of Viral Respiratory Pandemic

“…However, in 10–20% of cases they can progress to interstitial pneumonia and acute respiratory distress syndrome (ARDS), especially in those with advanced age and associated comorbidities [ 25 ]. Since the COVID-19 pandemic first began in December 2019, SARS-CoV-2 has continuously evolved, with many variants emerging around the world [ 26 ]. These mutations, especially when they occur on the S gene encoding the spike protein (S), can affect both the viral entry into the target cells and the effectiveness of the antibodies [ 27 ].…”

PAD Inhibitors as a Potential Treatment for SARS-CoV-2 Immunothrombosis

“…Principally, existing literature has not tested the efficacy of PAD-4 inhibitors in inflammatory conditions, such as COVID-19 in human models. With the continuous discovery of SARS-CoV-2 variants, including but not limited to B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.1 (Kappa) B.1.617.2 (Delta), B.1.526 (Iota), B.1.351, A.23.1, and most recently, the highly convoluted B.1.1.529 (Omicron) (Callaway, 2021) [ 85 , 86 , 87 , 88 ], SARS-CoV-2 treatment and vaccination are both constantly challenged. Although specific mutations in the spike protein, including the B.1.1.7 and B.1.351 variants, are generally effectively neutralized by existing vaccines [ 85 ], the response of vaccines to other variants, including the P.1 andB.1.617.2 display significantly reduced neutralization of SARS-CoV-2, with other variants such as the B.1.1.529 posing as novel challenges toward herd immunity.…”

“…With the continuous discovery of SARS-CoV-2 variants, including but not limited to B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.1 (Kappa) B.1.617.2 (Delta), B.1.526 (Iota), B.1.351, A.23.1, and most recently, the highly convoluted B.1.1.529 (Omicron) (Callaway, 2021) [ 85 , 86 , 87 , 88 ], SARS-CoV-2 treatment and vaccination are both constantly challenged. Although specific mutations in the spike protein, including the B.1.1.7 and B.1.351 variants, are generally effectively neutralized by existing vaccines [ 85 ], the response of vaccines to other variants, including the P.1 andB.1.617.2 display significantly reduced neutralization of SARS-CoV-2, with other variants such as the B.1.1.529 posing as novel challenges toward herd immunity. The B.1.617.2 variant, initially identified in India [ 89 ], possesses mutations granting enhanced transmissibility and producing more severe symptoms characteristic of higher viral loads within the respiratory tract, in addition to a unique symptom of gangrene secondary to severe blood clots.…”

“…With the continuous discovery of SARS-CoV-2 variants, including but not limited to B. [85], the response of vaccines to other variants, including the P.1 andB.1.617.2 display significantly reduced neutralization of SARS-CoV-2, with other variants such as the B.1.1.529 posing as novel challenges toward herd immunity. The B.1.617.2 variant, initially identified in India [89], possesses mutations granting enhanced transmissibility and producing more severe symptoms characteristic of higher viral loads within the respiratory tract, in addition to a unique symptom of gangrene secondary to severe blood clots.…”

When stem cells meet COVID-19: recent advances, challenges and future perspectives

“…The effectiveness and safety of vaccines are still issues that need to be concerned. And similar with other viruses, SARS-CoV-2 accumulates nucleotide mutations over time [ 32 ]. Along with its further diffusion, more variants may continue to emerge, which may be subject to selective pressures from natural immunity, vaccines and therapeutic drugs.…”