SARS-CoV-2 Variants: Impact of Spike Mutations on Vaccine and Therapeutic Strategies

In recent times, several variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, namely, B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2. (Delta), have arisen independently around the globe. Such a global emergence of variants has imposed unexpected burden on the health-care system, including ongoing vaccination efforts and operational decisions on vaccine distribution and essential medical supplies. These variants exhibit increased transmissibility and immune escape to convalescent sera and vaccines in addition to posing risk of increased disease severity and hospitalization. The efficacy of ongoing vaccine and therapeutic interventions against these newly identified variants are under clinical evaluation. This chapter discusses emerging SARS-CoV-2 variants, including variants of interest (VOI) and variants of concern (VOC). It also discusses the acquired genetic alterations accumulated by these variants in the spike protein and their impacts on protein structure and antigenicity. In addition, effects of these variants on vaccine efficacies and different therapeutic modalities as well as their clinical implication are discussed in this chapter.