Covid-19 Coronavirus outbreak.explanations analysis

Covid-19 Coronavirus outbreak: explanations, analysis and advice

Today we are offering this post dedicated to the Coronavirus epidemic Coronavirus Disease 2019” or “Covid-19” to be more precise, which was first named nCoV-2019), so that you can have access to main information.

I. The Coridovirus of the Covid-19 epidemic

The effects of coronavirus being sometimes compared to those of influenza, here is some detailed information.

1.1 “Simple” flu

Seasonal flu is an acute respiratory infection caused by an Influenza virus.
Covid-19 Coronavirus outbreak.explanations analysis

Influenza virus
Remember that each year, the flu affects between 2 million and 6 million people in France. Seasonal flu usually manifests as a sudden onset with high fever, intense fatigue, body aches and headaches. Most people recover within one to two weeks without medical treatment. It is then a "simple" flu .

1.2 Acute influenza

However, the flu can lead to serious complications in people at risk (elderly people or people weakened by a chronic disease, pregnant women or even premature infants). Mortality from seasonal flu mainly affects the elderly. These complications are due to the viruses themselves, but also to the bacterial superinfections (pneumonia) that they can cause or to the decompensation of an underlying chronic pathology (diabetes, asthma, heart disease, renal failure, etc.).
Influenza is the second leading cause of death from infectious disease in France (behind pneumococcal pneumonia). Between 2016 and 2019, it caused the death of 8,000 to 16,000 people depending on the year , 90% of those over 65 years of age. Globally, seasonal influenza is responsible for 290,000 to 650,000 deaths per year according to the World Health Organization ( source ).
The lethality (the number of deaths compared to the infected population) of seasonal flu is 0.2 to 0.5% according to Public Health France .
Influenza, which passes for a mild illness, is in fact a real public health problem.

1.3 The Spanish flu of 1918

In 1918-1919, the so-called “ Spanish flu ” pandemic   affected the whole world. It is not Spanish, as it was born in the United States, and was brought to Europe by soldiers in 1917-1918 - but Spain was the first to speak of it (due to the censorship due to war in other countries). WHO estimates indicate that at least 40 million people have died, including 400,000 in France (including Guillaume Apollinaire or Edmond Rostand; source here , there , there and there ).
This flu had a high lethality, from 2% to 3% ; in addition, half of the deaths were adults aged 20 to 40, while the classic flu almost exclusively infants and the elderly. It was also characterized by very high contagiousness (one third of the world's population was affected). Most of the victims died of bacterial superinfection, which appeared after 4-5 days and led to death ten days after the first flu symptoms, in the absence, at the time, of antibiotics.

1.4 SARS-CoV-2 coronavirus

Coronaviruses have existed for millions of years and have caused particular concern since 2002, the year of SARS (Severe Acute Respiratory Syndrome in English - caused by the SARS-CoV virus).
The new virus which caused the Covid-19 epidemic was named SARS-CoV-2 (ie "2nd SARS virus") is a new form of coronavirus: it appeared in December 2019 in China, on the Wuhan animal market, where all the first patients were infected. It probably comes from mutations in the bat coronavirus, following a passage in another animal host which remains to be defined.
The SARS-CoV genome consists of a single RNA approximately 30,000 nucleotides long, which includes 13 genes, which code for at least 14 proteins. The overall genomic organization of SARS-CoV is similar to that of other coronaviruses. source )
When a person infected with a coronavirus sneezes, droplets of nasal secretions loaded with viral particles are projected around them. If a healthy person gets splashed and breathes droplets containing coronaviruses, a new infection begins. Initially, the viruses penetrate into the nasal cells thanks to a protein "key": protein S (from the English Spike , "tip, ear"). Present in numerous copies on the surface of the virus, it gives it the appearance "in a crown" (under the microscope) to which it owes its name, coronavirus.
Covid-19 Coronavirus outbreak.explanations analysis
Protein S of coronaviruses gives them their very special appearance in microscopy (here the MERS-CoV)
This "key" interacts with a "lock" located on the surface of human cells, allowing the virus to cling to it and then enter it. Not all coronaviruses have the same types of keys, and therefore do not recognize the same locks. Once inside a cell, the coronavirus pirates it and forces it to make a large number of copies of itself. After a relatively short time, 6 or 8 hours later, these copies leave the infected cell (usually by destroying it) and go to attack its neighbors.
Covid-19 Coronavirus outbreak.explanations analysis
This scanning electron microscope image shows SARS-CoV-2 (blue spheres) emerging from cells grown in the laboratory (colorized image). NIAID-RML
As with SARS-CoV and MERS-CoV, SARS-CoV-2 can cause respiratory infections whose manifestations range from a simple cold to a severe respiratory syndrome, which may require intubation and ventilation. In short, as communicated by the WHO and in sequence, the symptoms of Covid-19 are fever (88%), dry cough (68%), fatigue (38%), sputum production (33%), shortness of breath (19%), sore throat (14%), headache (14%), muscle pain (15%), chills (11%), nausea or vomiting (5%), nasal congestion (5%) and diarrhea (4%). Some infected patients have no symptoms and report feeling well (4, 5). Recent studies show that 80-85% of people infected with SARS-CoV-2 have few or no symptoms, while 15 to 20% develop a more severe disease, often associated with old age or other comorbidities. ((source )
Finally, and this is the most worrying point, about 5% of infected subjects enter a critical phase of the disease and are admitted to the infectious disease and medical resuscitation departments, with a mortality rate of around 50% in this group. source ) Indeed, in their most severe forms, SARS-CoV-2 pneumonia is responsible for a picture called acute respiratory distress syndrome (ARDS). It involves an attack on the 2 lungs with severe inflammation leading to the destruction of the pulmonary alveoli as well as significant edema. source )
In summary, in these extreme cases, unlike the flu that kills rather indirectly by weakening the body, the Covid-19 virus will completely destroy the cells of the lungs - but it can also attack other organs, like the kidneys. Chinese doctors have also just attempted the first double lung transplant on a patient from Covid-19, who had received respiratory assistance, had finally eliminated the virus, but had suffered irreversible lung damage ( source ).

To date, there is still no vaccine or specific antiviral medication to prevent or treat COVID-19. However, affected people should receive care to relieve symptoms.
Possible vaccines and certain specific treatments are currently being studied and are being tested in clinical trials (more than 200!). WHO is coordinating efforts to develop vaccines and drugs to prevent and treat COVID-19. source )
But until an effective treatment has not been recognized by the medical community, we must neither believe nor even less spread the rumors and isolated peremptory statements that are starting to flourish on social networks. This can be dangerous or simply annoy caregivers, who are already under severe strain.
Covid-19 Coronavirus outbreak.explanations analysis

1.5 Lethality of SARS-CoV-2 coronavirus

The first studies suggest that this Coronavirus, as for the Spanish flu, would have a lethality of 2% to 3% , and a fairly high contagiousness, greater than that of the seasonal flu.

Here are the results of a Chinese study (whose transposition in France is not obvious) on almost 45,000 cases ( source ):

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