SARS-CoV-2 Variants and Vaccination

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused global destruction since its emergence in late 2019. Over the past 2 years, the virus has continually evolved in human hosts, thus leading to the emergence of variants with altered viral transmission, disease severity, and evasion of immunity. Although vaccines for coronavirus disease 2019 (COVID-19) have been developed at an unprecedented pace, the emergence of variants has posed a constant threat to the effectiveness of the approved vaccines. In this Commentary, we review the key variants and discuss their implications in viral replication, transmission, and immune evasion.