Epidemiology and Characteristics of SARS-CoV-2 Variants of Concern: The Impacts of the Spike Mutations

Abstract

SARS-CoV-2 expresses on its surface the Spike protein responsible for binding with the ACE2 receptor and which carries the majority of immunodominant epitopes. Mutations mainly affect this protein and can modify characteristics of the virus, giving each variant a unique profile concerning its transmissibility, virulence, and immune escape. The first lineage selected is the B.1 lineage characterized by the D614G substitution and from which all SARS-CoV-2 variants of concern have emerged. The first three variants of concern Alpha, Beta, and Gamma spread in early 2021: all shared the N501Y substitution. These variants were replaced by the Delta variant in summer 2021, carrying unique mutations like the L452R substitution and associated with higher virulence. It was in turn quickly replaced by the Omicron variant at the end of 2021, which has predominated since then, characterized by its large number of mutations. The successive appearance of variants of concern showed a dynamic evolution of SARS-CoV-2 through the selection and accumulation of mutations. This has not only allowed progressive improvement of the transmissibility of SARS-CoV-2, but has also participated in a better immune escape of the virus. This review brings together acquired knowledge about SARS-CoV-2 variants of concern and the impacts of the Spike mutations.

Safety and immunogenicity and efficacy of the self-amplifying mRNA ARCT-154 COVID-19 vaccine

“…24 Due to the high level of vaccination coverage with waning immunity, the current need for COVID-19 vaccines is to re-establish population immunity to protect against the emerging variants still causing outbreaks. 4 As such, ARCT-154 is most likely to be used as a booster dose, rather than for primary immunization, to enhance and broaden the level of immunity against circulating variants. A parallel study in Japan has shown that in adults fully immunized with mRNA vaccines, mainly BNT162b2, as primary vaccine, the immune response to a booster dose of ARCT-154 was superior to that of a booster dose of BNT162b2 when measured as neutralizing antibodies against Wuhan-Hu-1 and the Omicron 4/5 subvariant.…”

“…2 Accumulation of mutations in the spike glycoprotein (S protein), the main antigenic target, has made each successive new variant less susceptible to vaccine-induced immunity, 3 which combined with waning vaccine immunity has contributed to declining effectiveness of the currently available vaccines against new variants. [4][5][6][7][8] The most recently emerged Omicron variants cause less severe disease but are more infectious and easily transmissible, 9,10 leading to concerns that future variants may combine their high transmissibility with the severe disease of the original virus. These concerns are driving development of new vaccines that can elicit both greater breadth against new variants and longer duration of immunity to maintain protection against future COVID outbreaks.…”

Exigency of Plant-Based Vaccine against COVID-19 Emergence as Pandemic Preparedness

“…Due to increasing transmissibility, reducing antibody neutralization ability, and severe pathogenicity, these variants were considered as variants of concern (VOCs), while numerous newly evolved strains, including Epsilon (B. 1.427 2) because of the potential risk they may pose [47]. The emergence of new variants of SARS-CoV-2 is an ongoing process, and some of these variants may become more stable and infectious.…”

Efficiency of continuous positive airway pressure and high-flow nasal oxygen therapy in critically ill patients with COVID-19

“…Omicron, however, showed even higher transmissibility and greater immune escape than Delta. 15 The Omicron variants (BA.2 and BA.5) produce less severe disease than the Alpha and Delta variants. 16 Conventional oxygen therapy is insufficient for most patients with COVID-19 in the ICU.…”