Coronavirus (SARS-CoV-2) is of significant concern worldwide, but what exactly is the virus, what does it cause and what is the concern?

What is SARS-CoV-2?

The phrase coronavirus has been used many times, technically whilst the virus is a coronavirus this phrase refers to the family of viruses rather than the specific virus itself. coronaviruses are a large family of viruses, some of these viruses cause illness in humans whilst others cause illness in animals (e.g. bats). Rarely, animal coronaviruses can evolve to spread among humans which can cause severe diseases [1].

In the case of the 2019 coronavirus outbreak, the specific virus itself is referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), this virus is responsible for a respiratory disease called COVID-19.

What are the symptoms?

The symptoms vary but are generally of a respiratory nature and can include fever, flu like symptoms (e.g. coughing, sore throat, fatigue) and shortness of breath. [2] A more in depth analysis by the WHO report the symptoms as per the below [5];

“As of 20 February 2020 and based on 55924 laboratory confirmed cases, typical signs and symptoms include: fever (87.9%), dry cough (67.7%), fatigue (38.1%), sputum production (33.4%), shortness of breath (18.6%), sore throat (13.9%), headache (13.6%), myalgia or arthralgia (14.8%), chills (11.4%), nausea or vomiting (5.0%), nasal congestion (4.8%), diarrhea (3.7%), and hemoptysis (0.9%), and conjunctival congestion (0.8%).”

How is it spread?

Whilst the spread mechanism of SARS-CoV-2 is not fully known, the virus is thought to spread mainly through person to person. This can include [3];

• Between people who are in close contact with one and another.
• Through respiratory droplets produced when an infected person coughs or sneezes.
• It is also thought that the virus can spread through contact with contaminated surfaces.

A meta analysis by G. Kampf et al of 22 studies involving other coronaviruses determined that “Human coronaviruses can remain infectious on inanimate surfaces at room temperature for up to 9 days. At a temperature of 30°C or more the duration of persistence is shorter.” [4]. (Editorial: This may not be full viability but rather the presence of viral fragments which may or may not be virulent).

How long until symptoms occur?

The WHO reports that [5]; “People with COVID-19 generally develop signs and symptoms, including mild respiratory symptoms and fever, on an average of 5-6 days after infection (mean incubation period 5-6 days, range 1-14 days)”.

Who is most at risk of infection?

The groups of people with the highest risk of severe disease and death include people aged over 60 years as well as those with underlying conditions (e.g. hypertention, diabeters, cardiovascular disease, chronic respiratory disease and cancer). Disease in children is considered rare and mild with around 2.4% of cases reported amongst individuals under 19 years. A small proportion of those have developed severe (2.5%) or critical (0.2%) disease. [5]

What is the spread rate?

One of the terms used is R0 (or R-naught), this is a measure of how contagious an infectious disease is, whilst the R0 number for SARS-CoV-2 varies, the WHO report [5] places it at around 2 – 2.5 which means that on average, each infected person will spread it between 2 – 2.5. TO put it in perspective the R0 value for Measles is 12 – 18, whilst the pandemic (H1N1) 2009 influenza virus has a R0 of 1.2 to 1.6 [7].

It should be noted that the R0 value is not fixed and may differ in regions.

What is the mortality rate?

The WHO estimates (as of 5th March 2020) place the mortality rate at 3.4%, this is compared to around 1% mortality rate for the seasonal flu [8]. There is some speculation that this number may be inflated, as a proportion of the population may not seek medical treatment and recover but not be counted in the statistics.

Evolution of SARS-CoV-2?

Research is indicating that there may be two variants of SARS-CoV-2, this includes the L type in addition to the S type. The S type is suggested to be the ancestral type of the virus and is present in around 30% of cases, whilst the L type is more aggressive and is more prevalent in around 70% of cases [9].

*Disclaimer: The following is information I have compiled, its accuracy cannot be guaranteed and it is not designed to provide advice and/or medical information. Digest at your own risk.

References & Endnotes:

[1] https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/naming-the-coronavirus-disease-(covid-2019)-and-the-virus-that-causes-it

[2] https://www.health.gov.au/health-topics/novel-coronavirus-2019-ncov

[3] https://www.cdc.gov/coronavirus/2019-ncov/about/transmission.html

[4] https://www.journalofhospitalinfection.com/article/S0195-6701(20)30046-3/fulltext

[5] https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf

[6] https://en.wikipedia.org/wiki/Basic_reproduction_number

[7] https://www.who.int/influenza/resources/research/research_agenda_influenza_stream_2_limiting_spread.pdf

[8] https://www.worldometers.info/coronavirus/coronavirus-death-rate/#who-03-03-20

[9] https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463?searchresult=1