SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2)[2] is a strain of coronavirus that causes COVID-19, the respiratory illness responsible for the COVID-19 pandemic.[3] The virus previously had the provisional name 2019 novel coronavirus (2019-nCoV),[4][5][6][7] and has also been called human coronavirus 2019 (HCoV-19 or hCoV-19).[8][9][10][11] First identified in the city of Wuhan, Hubei, China, the World Health Organization designated the outbreak a public health emergency of international concern from January 30, 2020, to May 5, 2023.[12][13][14] SARS‑CoV‑2 is a positive-sense single-stranded RNA virus[15] that is contagious in humans.[16]
This article is about the virus that causes COVID-19. For the virus that causes SARS, see SARS-CoV-1.
SARS‑CoV‑2 is a strain of the species severe-acute-respiratory-syndrome-related coronavirus (SARSr-CoV), as is SARS-CoV-1, the virus that caused the 2002–2004 SARS outbreak.[2][17] There are animal-borne coronavirus strains more closely related to SARS-CoV-2, the most closely known relative being the BANAL-52 bat coronavirus. SARS-CoV-2 is of zoonotic origin; its close genetic similarity to bat coronaviruses suggests it emerged from such a bat-borne virus.[18] Research is ongoing as to whether SARS‑CoV‑2 came directly from bats or indirectly through any intermediate hosts.[19] The virus shows little genetic diversity, indicating that the spillover event introducing SARS‑CoV‑2 to humans is likely to have occurred in late 2019.[20]
Epidemiological studies estimate that in the period between December 2019 and September 2020 each infection resulted in an average of 2.4–3.4 new infections when no members of the community were immune and no preventive measures were taken.[21] However, some subsequent variants have become more infectious.[22] The virus is airborne and primarily spreads between people through close contact and via aerosols and respiratory droplets that are exhaled when talking, breathing, or otherwise exhaling, as well as those produced from coughs and sneezes.[23][24] It enters human cells by binding to angiotensin-converting enzyme 2 (ACE2), a membrane protein that regulates the renin–angiotensin system.[25][26]
Treatment and drug development
Very few drugs are known to effectively inhibit SARS‑CoV‑2. Masitinib is a clinically safe drug and was recently found to inhibit its main protease, 3CLpro and showed >200-fold reduction in viral titers in the lungs and nose in mice. However, it is not approved for the treatment of COVID-19 in humans as of August 2021.[168] In December 2021, the United States granted emergency use authorization to Nirmatrelvir/ritonavir for the treatment of the virus;[169] the European Union, United Kingdom, and Canada followed suit with full authorization soon after.[170][171][172] One study found that Nirmatrelvir/ritonavir reduced the risk of hospitalization and death by 88%.[173]
COVID Moonshot is an international collaborative open-science project started in March 2020 with the goal of developing an un-patented oral antiviral drug for treatment of SARS-CoV-2.[174]