SARS‑CoV‑2 is a virus of the species severe acute respiratory syndrome–related coronavirus (SARSr-CoV), related to the SARS-CoV-1 virus that caused the 2002–2004 SARS outbreak.   Despite its close relation to SARS-CoV-1, its closest relatives, with which it forms a sister group, are the derived SARS viruses BANAL-52 and RaTG13. 
SARS-CoV-2 genetic lineages in the United States are routinely monitored through epidemiological investigations, virus genetic sequence-based surveillance, and laboratory studies. On November 30, 2021, the U.S. government SARS-CoV-2 Interagency Group (SIG) classified Omicron as a Variant of Concern (VOC).
SARS-CoV-2 reinfection has been reported in people after an initial diagnosis of the infection; therefore, clinicians should consider using a NAAT for those who have recovered from a previous infection and who present with symptoms that are compatible with SARS-CoV-2 infection if there is no alternative diagnosis ( BIII ).
SARS-CoV-2 is transmitted by exposure to infectious respiratory fluids The risk of SARS-CoV-2 infection varies according to the amount of virus to which a person is exposed Transmission of SARS-CoV-2 from inhalation virus in the air farther than six feet from an infectious source can occur Prevention of COVID-19 transmission References
SARS-CoV-2 The virus that causes a respiratory disease called coronavirus disease 19 (see definition COVID-19). SARS-CoV-2 is part of a larger family of viruses called coronaviruses, including SARS-CoV, which led to an epidemic that affected 26 countries and resulted in more than 8000 cases in 2003. RELATED FAQ:
We describe how SARS-CoV-2 may infect the lower respiratory tract and cause alveolar damage as a result of dysfunctional immune responses. We discuss how this may lead to the induction of a 'leaky state' of both the epithelium and the endothelium, promoting inflammation and coagulation, while an influx of immune cells leads to overexuberant ...
There are many variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some are believed, or have been stated, to be of particular importance due to their potential for increased transmissibility,  increased virulence, or reduced effectiveness of vaccines against them.