Coronavirus disease 2019 (COVID-19) is a highly contagious viral illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has had a catastrophic effect on the world resulting in more than 6 million deaths worldwide. After the first cases of this predominantly respiratory viral illness were first reported in Wuhan, Hubei Province, China, in late December 2019, SARS-CoV-2 rapidly disseminated across the world in a short span of time. This compelled the World Health Organization (WHO) to declare it as a global pandemic on March 11, 2020. Even though substantial progress in clinical research has led to a better understanding of SARS-CoV-2, many countries continue to have outbreaks of this viral illness that are attributed to the emergence of mutant variants of the virus.
Like other RNA viruses, SARS-CoV-2, while adapting to their new human hosts, is prone to genetic evolution with the development of mutations over time, resulting in mutant variants that may have different characteristics than its ancestral strains. Several variants of SARS-CoV-2 have been described during the course of this pandemic, among which only a few are considered variants of concern (VOCs) by the WHO, given their impact on global public health. Based on the epidemiological update by the WHO, five SARS-CoV-2 VOCs have been identified since the beginning of the pandemic:
Despite the unprecedented speed of vaccine development against the prevention of COVID-19 and robust global mass vaccination efforts including vaccine boosters, the emergence of these new SARS-CoV-2 variants threatens to overturn the significant progress made so far in limiting the spread of this viral illness.