The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused global destruction since its emergence in late 2019. Over the past two years, the virus has continuously evolved in human host, leading to emergence of variants with changed viral transmission, disease severity, and evasion of immunity. Although vaccines have been developed for the coronavirus disease 2019 (COVID-19) at an unprecedently pace, the variants have constantly posed threats to the effectiveness of the approved vaccines. In this short communication, we review the key variants and discuss their implications in viral replication, transmission, and immune evasion.
Keywords: COVID-19; SARS-CoV-2 variants; neutralization; spike mutations; vaccine.