SARS-CoV-2, previously known as the 2019-nCoV, is a positive-sense, single-stranded RNA coronavirus first reported in late 2019 and linked in the 2019-2020 pneumonia outbreak in Wuhan City in central China and the COVID-19 outbreak across the globe. The virus was genetically sequenced after a nucleic acid testing on a sample from a patient affected with pneumonia of unknown cause.
Origin of the SARS-CoV-2: The 2019-2020 Coronavirus Outbreak
Beginning in mid-December in 2019, several reports documented a cluster of people with pneumonia of unknown cause. These infected individuals were stallholders who worked at the Huanan Seafood Wholesale Market in Wuhan City, the capital of Hubei Province in China. Note that the market also sells live animals.
According to an editorial by D. S. Hui et al. published by the International Journal of Infectious Diseases, Chinese health authorities first described the disease as something similar to other infections caused by human coronaviruses such as the Severe Acute Respiratory Syndrome or SARS caused by SARS-CoV and the Middle East Respiratory Syndrome or MERS caused by MERS-CoV.
Note that coronaviruses circulate chiefly among animals. However, they have been known to evolve and spillover or jump to infect humans, such as in the case of SARS, MERS, and four other coronaviruses that cause mild respiratory symptoms in human population.
Chinese authorities ruled out SARS-CoV and MERS-CoV, as well as influenza, avian influenza, and other common respiratory viruses. Public measures were undertaken in Huanan, including epidemiological investigations, closure of the public market, isolation of people with symptoms, and monitoring of 700 people that included 400 healthcare workers.
It is also worth noting that the Huanan Seafood Wholesale Market is a wholesale animal and fish market with about 1000 stalls selling butchered and live chickens, cats, pheasants, bats, marmots, venomous snakes, spotted deer, as well as the organs of rabbits and other wild animals. Hence, this led to a suspicion that the virus originated from an animal source.
There are also sensational claims that the novel coronavirus originated from a the Wuhan Institute of Virology, accidentally leaking either as a bioweapon or an experimental pathogen engineered as part of coronavirus research. However, these claims remain unsubstantiated.
Nonetheless, on 7 January 2020, Chinese scientists were able to isolate the virus from an infected patient and perform genome sequencing. The sequence became available to the World Health Organization on 12 January 2020, thus facilitating laboratories from different countries to produce specific diagnostic RT-PCR tests for novel infections.
Virology of SARS-CoV-2: Naming, Description as a Coronavirus, and Similarities
The WHO initially recommended the name 2019-nCoV for the novel coronavirus. Health officials and international media have also labeled the virus as the Wuhan coronavirus and Wuhan seafood market virus. The absence of an official name raised concerns over the use of prejudicial informal names and confusing common parlance.
Nonetheless, in referencing the 2015 WHO naming guidelines, the International Committee on Taxonomy of Viruses introduced the name “severe acute respiratory syndrome coronavirus 2” or SARS-CoV-2 on 11 February 2020.
A genetic sequence revealed that SARS-CoV-2 is a beta coronavirus of group 2B with at least 70 percent similarity with SARS-CoV. Its RNA sequence is approximately 30 kbp in length. A report by Jon Cohen and Dennis Normile also noted that the virus closely resembles four bat coronaviruses.
The China CDC National Institute for Viral Disease Control and Prevention, Institute of Pathogen Biology, and Wuhan Jinyintan Hospital also isolated and reported five genomes of 2019-nCoV. These are BetaCoV/Wuhan/IVDC-HB-01/2019, BetaCoV/Wuhan/IVDC-HB-04/2020, BetaCoV/Wuhan/IVDC-HB-05/2019, BetaCoV/Wuhan/WIV04/2019, and BetaCoV/Wuhan/IPBCAMS-WH-01/2019.
Because it is part of the coronavirus family, its virology and morphology are generally similar to other coronaviruses such as SARS-CoV and MERS-CoV. Hence, it is also an enveloped virus with a positive-sense single-stranded RNA genome and with a nucleocapsid of helical symmetry. Note that coronaviruses have large pleomorphic spherical particles with bulbous surface projections that form a corona around particles
COVID-19 Outbreak: Mode of Transmission and Signs and Symptoms
Researchers have confirmed that the mode of transmission of SARS-CoV-2 is human-to-human due to the way the disease has spread outside Wuhan City. For example, reports confirmed that a 61-year-old Wuhan tourist who traveled to Thailand was diagnosed to have pneumonia caused by the virus on 13 January 2020. More recents studies have indicated that the virus is alsoairborne, thus allowing it to travel for longer distance.
The tourist mentioned that she never visited the Huanan Wholesale Seafood Market but also noted that she visited other markers in Wuhan prior to her trip to Thailand. On 20 January, more confirmed cases were reported in the southern province of Guangdong and two in Beijing.
Reports confirmed another case in South Korea and further cases in Guangdong and Beijing. Hence, the rate at which the disease spreads has left healthcare researchers and professionals to worry about the capacity of the virus to travel quickly outside of China and across megacities.
The initial publicized cases in Wuhan has been tagged conservative as well. According to a report published by the infectious disease research center of Imperial College London, the number of initial infections within the city alone should be in the range of 1700 cases. Note that the researchers ran running a statistical analysis and extrapolation from the presence of overseas cases
The specific disease arising from SARS-CoV-2 infection was generally called 2019-nCoV Acute Respiratory Disease, or 2019-nCoV ARD. However, on 11 February 2020, WHO officially named the associated disease as coronavirus disease 2019 or COVID-2019.
Note that those infected may either be asymptomatic or have symptoms. Hence, instead of calling the disease as SARS-2, coronavirus disease 2019 is a more suitable naming. Documented reports revealed that clinical signs and symptoms are fever, cough, tightness of the chest, and difficulty with breathing. Some chest scans indicated inflamed and fluid-filled lungs. Other documented and studied clinical presentations of COVID-19 revealed include gastrointestinal problems, loss of sense of smell and tase, and conjunctivitis.
As with other coronaviruses, as well as diseases such as the common cold, there is no drug available drug for treating the disease or a vaccine for acquiring adaptive immunity against SARS-CoV-2. Current therapeutic strategies focus on relieving symptoms. Nonetheless, because it can cause respiratory problems, the virus can spread through coughing, exposure to mucous discharges, or when someone touches a contaminated surface. Individuals with compromised health, such as those with preexisting conditions, immunocompromised, and the elderly are more vulnerable to severe cases and possible fatalities.
FURTHER READINGS AND REFERENCES
- Cohen, J. & Normile, D. 2020. “New SARS-like Virus in China Triggers Alarm.” Science. 367(6475): 234-235. DOI: 1126/science.367.6475.234
- Hui, D. S. et al. 2020. “The Continuing 2019-nCoV Epidemic Threat of Novel Coronaviruses to Global Health – The Latest 2019 Novel Coronavirus Outbreak in Wuhan, China.” International Journal of Infectious Disease. 91(2020): 264-266. DOI: 1016/j.ijid.2020.01.009
- Imai, N., Dorigatti, I., Cori, A., Riley, S., & Ferguson, N. M. 2020, January 17. “Estimating the Potential Total Number of Novel Coronavirus Cases in Wuhan City, China.” Imperial College London News. Imperial College, MRC Centre for Global Infectious Disease Analysis. Available online
- Konsyse Staff. 2020. “Facts: 2019-nCoV is Not a Lab-Made Bioweapon from China.” Konsyse. Available online
- Konsyse Staff. 2020. “Fast Facts: The 2019-nCoV and Wuhan Pneumonia Outbreak.” Konsyse. Available online.
