Caused by the SARS-CoV-2 coronavirus, Covid-19 disease has already affected more than 119,000 patients worldwide and caused more than 4,000 deaths. Mutation of the virus, flu-like symptoms, contagion, transmission, screening test … Identity card to date.
At the end of 2019, grouped cases of pneumonia occurred in China, some of them fatal. January 9, the virus responsible is identified, it is a new coronavirus. It is highly contagious. In March, this virus spread on 5 continents and affected more than 100 countries, more than 119,000 people and left nearly 4,300 dead. What did the researchers find out about him?
After being baptized nCoV-2019 in a first, this new coronavirus was called SARS-CoV-2 (SARS for “Severe Acute Respiratory Syndrome” and CoV for “CoronaVirus”). His illness was named Covid-19 February 11, 2020 to be “easier to pronounce” had justified the director general of WHO Tedros Adhanom Ghebreyesus.
Meaning : “Co” means “corona”, “vi” for “virus” and that “D” for “disease”. The number 19 indicates the year of its appearance: 2019. “We had to find a name that did not refer to a geographic location, an animal, an individual or a group of people” added the general manager, to avoid any stigmatization of the disease.
SARS-CoV-2 belongs to the family of coronavirus (with a large number of viruses) which can cause mild illnesses in humans such as colds and more serious pathologies as the Sras. The contamination isanimal origin. The epidemic started from a local market in Wuhan, China, where wild animals were sold. On February 7, 2020, scientists from the Southern China University of Agriculture identified the pangolin as a “possible intermediate host” suspected of having transmitted the coronavirus to humans. The pangolin is a small mammal covered with scales threatened with extinction, whose delicate flesh is highly prized in Chinese and Vietnamese gastronomy. In a press release, scientists explain that an animal can carry a virus without being sick and transmit it to other species such as humans. After analyzing 1,000 samples, scientists were able to show that the genomes of virus sequences taken from pangolins were 99% identical to viruses found in people with nCoV, says Chine Nouvelle. Recall that during the 2002-2003 SARS epidemic, the intermediate host of the virus was the civet, a small animal with a gray coat whose meat is eaten in China.
According to the latest scientific data, there are indeed two circulating strains of the virus (L and S).
- The S strain is said to be older than the L strain. At this stage, there is nothing to confirm whether the mutation took place in humans or in intermediate hosts (animals).
- The L strain would be the most severe and frequent circulating strain (70% of the samples tested in the study), while the S strain would be less aggressive and less frequent (30% of the samples).
“Thanks to the means of detection and the measures to combat the coronavirus, the circulation of the L strain, more severe and therefore more easily detectable, tends to decrease” indicates the government on its site.
The peculiarity of the new coronavirus, in comparison to Sras or the Mers virus, is its contagion. “The SARS coronavirus was contagious only a few days after the onset of symptoms, 4 days later. This left time to diagnose and isolate the patients before they contaminated other people. all the patients had severe forms so they were all identified, we did not miss benign forms which could have been unnoticed. With this coronavirus, contagion begins with the onset of symptoms and sometimes in people who do not have symptoms” explained Professor Arnaud Fontanet, epidemiologist at the Institut Pasteur during a round table in the Senate on February 26, 2020.
The average duration of incubation is 6 days with a maximum duration of 12 to 14 days.
Coronavirus that appeared in 2019 gives lung infections “with some signs of respiratory infection high or low, the low forms being those which expose to gravity and to what is called a acute respiratory distress syndrome that is to say a failure of the respiratory functions “ explained Dr Catherine Leport, head of the Coreb mission in February 2020.
Among the symptoms observed in patients (which resemble those of the flu): fever, cough, fatigue, body aches and lung damage with, in the most severe cases, acute respiratory distress syndrome, i.e. respiratory failure.
To note : Unlike the SARS coronavirus, the forms of which were still severe, the coronavirus linked to the Covid-19 epidemic is associated with asymptomatic and benign forms with a more serious development after a week.
Like all coronaviruses, the new coronavirus is transmitted between humans by saliva, droplets (cough, sneezing), by close contact with patients (handshakes …) and by contact with contaminated surfaces. Regular hand washing (approximately every hour) and wearing masks help reduce the spread of the virus.
A diagnostic test developed by the national reference center for respiratory viruses (Institut Pasteur) is available in France to diagnose infection with this new coronavirus. It is currently performed by a specific laboratory technique on a nasopharyngeal swab whose results can usually be obtained in 4 hours. No commercial test is available. There is :
- systematic sampling of the upper respiratory tract (nasopharyngeal / Virocult® swabs or aspirations)
- a sample of the lower respiratory tract (sputum, LBA, ATB) in case of parenchymal involvement.
No treatment has proven its total effectiveness in combating SARS-CoV-2. But “there are lines of inquiry with two products which have been administered in a few French cases, said Catherine Leport, infectious disease specialist and member of the Coreb mission, on February 26 in the Senate. It’s about Remdesivir which had been developed for the Ebola hemorrhagic fever and an even older drug, Ritonavir which is a anti HIV medication“. The chloroquine could also be an “interesting product to test” according to the infectiologist.
With the coronavirus epidemic just beginning in France, researchers are busy developing a vaccine against this highly contagious virus. On RTL, a researcher from the Institut Pasteur indicated that tests on mice would start on Wednesday March 11: “The tests will last a month, a month and a half: we vaccinate mice, then we regularly take their blood to see if they have made antibodies against the vaccine. If they have made antibodies, we infect them with the coronavirus and we see if they resist.” The researchers hope to quickly put in place a vaccine.
Covid-19 has high mortality in adults. 80% of those who die are over 60. For children, these are mild clinical forms.
Sources:
- Management of biological samples from a suspect patient of Covid-19, French Society of Microbiology, 02/21/2020.
- Round table organized on February 26, 2020 in the Senate on the risks of coronavirus in France, in the presence of several experts.
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