SARS-CoV-2, the causative agent of the ongoing pandemic that started in 2019, has become the most well-known member of the coronaviruses.
Novel Coronavirus (2019-nCoV) / SARS-CoV-2
Human coronaviruses (HCoV) belong to the Coronaviridae family [1, 2]. The coronaviruses are enveloped, non-segmented positive-sense RNA viruses. They have the largest identified RNA genomes and contain approximately 30 kilobase (kb) genomes.
Human coronaviruses (HCoV) were first identified in the 1960s from the patients with the common cold. Coronaviruses primarily effect the upper respiratory and gastrointestinal tract of mammals and birds. Seven coronavirus strains (229E, NL63, OC43, HKU1, SARS-CoV, MERS-CoV and 2019-nCoV) are currently known in humans. The most known human coronavirus, SARS-CoV which causes SARS, has a unique pathogenesis because it infects both upper and lower respiratory tract infections .
Coronaviruses are associated with the common cold, pneumonia, and severe acute respiratory syndrome (SARS) and may also affect the gut. The symptoms may include: Headache, cough, sore throat, fever, sneeze and trouble breathing. The virus can be transmitted by one person to another through, the infected respiratory fluid.
The Centers for Disease Control and Prevention (CDC) confirmed the first case of 2019 Novel Coronavirus (2019-nCoV) in Washington, the United States on January 21, 2020. The patient recently returned from Wuhan, China, where an outbreak of pneumonia caused by the novel coronavirus has been ongoing since December 2019. A clinical specimen collected and sent to CDC, where laboratory testing confirmed the diagnosis via CDC’s Real time Reverse Transcription-Polymerase Chain Reaction (rRT-PCR) test. 
2019 Novel Coronavirus (2019-nCoV), which belongs to the same family as the pathogen that causes severe acute respiratory syndrome (SARS), is first identified as the cause of a respiratory illness outbreak detected in Wuhan, China . The World Health Organization (WHO) has officially named the disease caused by this coronavirus COVID-19. 2019 Novel Coronavirus (2019-nCoV) is renamed officially as Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) by WHO .
For confirmed 2019-nCoV infections, symptoms can include fever, cough, and difficulty in breathing ranging from mild symptoms to severe illness and death . Cases of severe infection can result in pneumonia, kidney failure, and death . According to CDC, symptoms of 2019-nCoV may appear in as few as 2 days or as long as 14 after exposure, however, it is thought to be contagious during this period or after recovery .
A diversification of SARS-CoV-2 due to evolution and adaptation processes has been observed globally and is expected to occur with ongoing transmission of viruses in general and particularly for RNA viruses.  Most mutations that emerge will not provide selective advantage to the virus. However, some mutations or combinations of mutations may provide the virus with a selective advantage, such as increased transmissibility through an increase in receptor binding or the ability to evade the host immune response by altering the surface structures recognized by antibodies.
A new SARS-CoV-2 virus variant is referred to in the UK as SARS-CoV-2 VUI 202012/01 (and now VUC-202012/01). It is defined by multiple spike protein mutations (deletion 69-70, deletion 144, N501Y, A570D, D614G, P681H, T716I, S982A, D1118H) present as well as mutations in other genomic regions.  Sample collected in other countries cluster with the UK variant, most likely indicating that international spread has occurred, although the extent remains unknown.
- De Groot RJ, Baker SC, Baric R, Enjuanes L, Gorbalenya AE, Holmes KV, Perlman S, Poon L, Rottier PJ, Talbot PJ, Woo PC, Ziebuhr J (2011). “Family Coronaviridae”. In AMQ King, E Lefkowitz, MJ Adams, EB Carstens. Ninth Report of the International Committee on Taxonomy of Viruses. Elsevier, Oxford. pp. 806–828. ISBN 978-0-12-384684-6.
- International Committee on Taxonomy of Viruses (24 August 2010). “ICTV Master Species List 2009 – v10” (xls).
- National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases https://www.cdc.gov/ncird/index.html.
- The Centers for Disease Control and Prevention (CDC), “First Travel-related Case of 2019 Novel Coronavirus Detected in United States” (21 January 2020). https://www.cdc.gov/media/releases/2020/p0121-novel-coronavirus-travel-case.html
- “About 2019 Novel Coronavirus (2019-nCoV)” Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/about/index.html Retrieved 12 February 2020.
- “Coronavirus latest: WHO officially names disease COVID-19” Nature. https://www.nature.com/articles/d41586-020-00154-w Retrieved 12 February 2020.
- van Dorp L, Richard D, Tan CCS, Shaw LP, Acman M, Balloux F. No evidence for increased transmissibility from recurrent mutations in SARS-CoV-2. Nature communications. 2020 Nov 25;11(1):5986.
- Andrew Rambaut, Nick Loman, Oliver Pybus, Wendy Barclay4, Jeff Barrett5, Alesandro Carabelli6, et al. Preliminary genomic characterisation of an emergent SARS-CoV-2 lineage in the UK defined by a novel set of spike mutations: COVID-19 genomics UK consortium; [20 December, 2020]. Available from: https://virological.org/t/preliminary-genomic-characterisation-of-an-emergent-sars-cov-2-lineage-in-the-ukdefined-by-a-novel-set-of-spike-mutations/563.