A systematic review of the variants of Sars-Cov-2

Before the end of December 2019, the epidemic was mainly localized in Wuhan, Hubei Province, China. Most of the cases in this stage were related to exposure to Huanan seafood market. "The virus is transmitted through human-to-human contact and rapidly spread across the world, and soon turned into a pandemic." Its symptoms can be divided to two main groups of majors (fever, cough, and dyspnea) and minors (anosmia, dysgeusia, headache, gastrointestinal symptoms, and skin lesions). Ever since, it has caused worldwide social and economic disruption, there are no universally recognized clinically useful antiviral drugs against COVID-19 so far (actually remdesivir showed good efficacy in many trials, but it needs to be further realized). Although there are several effective vaccines to prevent infection with SARS-CoV-2, efforts to develop medications and vaccines are continuing. Recently, a novel coronavirus, severe acute respiratory syndrome SARS-CoV-2, causing coronavirus disease 2019 (COVID-19), emerged in late 2019. During February 1-July 13, 2020, were identified 4,080 transmission pairs in Georgia, USA, by using contact tracing information from COVID-19 cases reported to the Georgia Department of Public Health. The novel coronavirus disease 2019 (COVID-19) outbreak and Italy has caused 6088 cases and 41 deaths in Republic of Korea and 3144 cases and 107 deaths in Italy by 5 March 2020. Currently, the following variants; Alpha, Beta, Gamma, Delta and Omicron were originated from United Kingdom, South Africa, Brazil/Japan, and India, respectively. The classification of SARS-CoV-2 variants is based on the mutations in the structure-based inclusions. Transmission varied not only by time and place but also by persons' sex and race. Younger adults (20–50 years of age) were involved in most transmission events.