ABSTRACT
SARS-CoV-2, a newly emerging coronavirus that caused the COVID-19 epidemic, has been spreading quickly throughout the world. Despite immunization and some fairly effective therapeutic regimens, SARS-CoV-2 has been ravaging patients, health workers, and the economy. SARS-CoV-2 mutates and evolves to adapt to its host as a result of extreme selection pressure. As a consequence, new SARS-CoV-2 variants have emerged, some of which are classified as variants of concern (VOC) because they exhibit greater transmissibility, cause more-severe disease, are better able to escape immunity, or cause higher mortality than the original Wuhan strain. Here, we introduce these VOCs and review their characteristics, such as transmissibility, immune escape, mortality risk, and diagnostics.