Covid-19 in Brief

Having emerged in Wuhan with a population of over 11.08 million people, the novel coronavirus (Covid‑19) is an infectious disease caused by the  SARS-CoV-2 coronavirus strain triggering severe respiratory issues in a certain proportion of humans. The generic name consists of a compound noun (corona+virus) pertaining to a virus with both mild and deadly strains resembling a corona (crown) when observed under microscopic conditions. Six previously classified coronavirus strains and SARS-CoV-2 (which prompted the latest pandemic) can render humans susceptible to severe illnesses by inflicting harm to different body parts, while most strains cause mild respiratory issues such as the common cold.

Coronavirus or Covid-19 Nomenclature

The International Committee on Taxonomy of Viruses (ICTV) generally name viruses with the support of virologists and the wider scientific community. However, different coronavirus terminology has appeared over time due to editorial, political, cultural or practical reasons as well as mere confusion. Corona Briefer observes that countries and institutions around the globe use various terms to allude to the pandemic including coronavirus, the novel coronavirus, 2019 novel coronavirus, Covid-19 (or Covid-19), SARS-CoV-2, severe acute respiratory syndrome coronavirus 2 (also formerly 2019-nCoV). When using the word form, we opt for “coronavirus” for a simplistic expression as the term coronaviruses or coronavirus strains refer to other types of the virus, and we prefer the abbreviation Covid-19 rather than capitalizing all the letters in Covid-19 (see this Guardian article to read further).

Identification of Covid-19

The novel strain of coronavirus, SARS-CoV-2, was initially classified in December 2019 in Wuhan, a Chinese city with a population of 11.08 million in Hubei province with 58.5 million residents amidst news that China was facing an outbreak that lacked an obvious cause.

Classification of Covid-19

The commonly known coronavirus disease, more specifically Covid-19, belongs to a family of RENA viruses called coronavirus. Scientists have divided coronaviruses as a RNA virus group into four genera: alpha, beta, gamma, and delta. Seven of them can infect people. Four human coronaviruses present generally mild symptoms: 229E (alpha), NL63 (alpha), OC43 (beta), HKU1 (beta). On the other hand, three human coronaviruses generate potentially severe symptoms: MERS-CoV, a beta virus that causes Middle East respiratory syndrome (MERS), SARS-CoV, a beta virus that causes severe acute respiratory syndrome (SARS) and SARS-CoV-2, which causes Covid-19.

How seven human coronaviruses differ from each other

The main distinction between coronaviruses is manifested in the severity of the ailments caused by them. The first 4 respiratory viruses range from mild to medium in contrast with Sars and Mers with both causing highly severe respiratory illness. However, the cases around the globe reveal that Sars-Cov-2, the seventh strain, ranges from mild-medium to severe. Molecular-wise, coronaviruses show certain variations in their genetic sequence in addition to the cellular receptor they deploy.

How Covid-19 inflicts great harm on human health

A virus is a protein box with genetic material inside which needs a living cell to replicate. It enters the cell by binding with receptors and reprograms to generate its copies as a template to replicate more viruses inside the body. When viruses infect you, they attach to your cells, get inside them, and make copies of their RNA, which helps them spread. If there’s a copying mistake, the RNA gets changed. Scientists call those changes mutations. In this case, Sars-Cov-2 uses ACE2 as receptors and entry point as mostly found in the respiratory tract. The virus infects the target cells inflicting damage. The subsequent inflammatory and immune response is prone to cause pneumonia to develop in most severe cases. The impact depends on the infected individual and how their body reacts.

The spread of Covid-19

Corona Briefer's understanding from the WHO and other sources is that the virus is mostly transmitted through contact routes and contaminated respiratory droplets. Droplets of saliva or mucus carrying the respiratory virus can travel 1-3 three meters when an individual coughs or sneezes. The virus needs to fully enter the respiratory tract for infection to happen. That is why one can reduce infection risk by avoiding close contact with sick people. Washing your hands thoroughly greatly reduces the risk of infection. There are reports that infection is possible through feces and recirculated air ventilation systems and air conditioners as this study on NCBI claims. But this has not been systematically investigated. Therefore, it is hard to say with 100 percent certainty.

Reinfection in Covid-19 after a successful recovery

Yes, people can become infected by Covid-19 again if enough time elapses and their natural immunity is no longer present or it is not effective anymore. In the case of the four other respiratory coronaviruses, cases of reinfections are observed after eight to 12 months.

How does Covid-19 compare with Sars, Mers, and the four coronaviruses that cause the common cold?

A February 2020 article by Jiang et al. highlighted that any comparative analysis of the incubation periods of SARS‐CoV‐2, SARS, and MERS depended on the selected data sources as the difficulty of finding relevant data extended to other significant SARS‐CoV‐2 characteristics such as the reproduction number, clinical symptoms, and transmission routes.

Another study reveals that the lung impressions of MERS and Covid-19 pneumonia are significantly different from SARS, while the network has identified similarities of deep layer features with ten MERS images as Covid-19. A lancet study published by Çevik et al. in November compared upper respiratory tract viral load of approximately 5350, 1850, and 800 SARS-CoV-2, SARS, and MERS cases, respectively. The viral load of the novel coronavirus peaked in the upper respiratory tract within the very first whereas the average period was found to be more than 7 days for both SARS and MERS.

Corona Briefer’s note: Please visit our news coverage for the latest updates and comprehensive analysis of the current coronavirus outbreak. For direct statistics, check our TRACKER page.