symptoms, people at risk, incubation, transmission

The more the epidemic progresses, the more the Covid-19 disease is exposed by scientists. We now know that it can occur without fever, cause diarrhea and other more serious symptoms. What is its incubation period? People most at risk for serious forms? The treatments used? What we know.

At the end of 2019, grouped cases of pneumonia occurred in China, some of them fatal. On January 9, virus responsible is identified, it is a new coronavirus called Sars-CoV-2. In March, this highly contagious virus spread over the 5 continents of the Earth and has contaminated more than a million people in more than 180 countries, killing 50,000. The more the epidemic progresses, especially in France, the more we know about this mysterious coronavirus …

After being baptized nCoV-2019 at 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 by the WHO to mean:

  • Co “means” corona “,
  • “vi” for “virus” and
  • “D” for “disease” (“illness” in English).

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” said WHO Director-General Dr Tedros Adhanom Ghebreyesus to avoid stigmatization of the disease.

The pangolin possible intermediate host of the coronavirus © 123RF- Rahmat Nugroho

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 is part of a Wuhan local market in China where were sold animals wild. Currently, it is still unclear which animal is responsible for it. It could be the bat where a virus very similar to Sars-CoV-2 was detected. 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. This small mammal consumed in southern China could be implicated as intermediate host between the bat and humans. The pangolin is a 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. The bat was also responsible for the transmission of viruses to humans, including SARS, MERS in Saudi Arabia, and also Ebola.

According to the latest scientific data, there are 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. This virus can mutate even if as pointed out by Dr. Gérard Kierzek “since December he hasn’t changed”. Before recalling that if the mutation of the virus worries, it is not necessarily more dangerous for humans: “The mutation can go both ways, towards more virulence or less virulence, more contagiousness, less contagiousness.”

Feel shortness of breath in simple activities at home is a warning sign.

The average incubation time is 4 days with a maximum duration of 12 to 14 days.

Unlike the flu that comes on suddenly, a coronavirus infection “is done gradually over several days” says the Pasteur Institute. Patients report symptoms that appear over a week and a fairly long healing time. “In more than 80% of cases, the signs are quite minor. They are angina or nasopharyngitis” indicated Professor Karine Lacombe, head of the infectious diseases department at the Saint-Antoine hospital in Paris, during a press conference on television on March 28, 2020.

First symptoms

→ Among the first symptoms of a coronavirus infection are signs of a cold or flu-like condition: a runny nose, a headache (sometimes violent in some coronavirus patients), body aches and tiredness.

→ Sometimes fever but not always. At the start of the epidemic, in the first cases of coronavirus, fever was a warning sign, as with many infections. Today, some people who are positive for the virus have little or no fever.

→ Patients also present red eyes with slight conjunctivitis.

“Feel shortness of breath in simple activities at home is a sign that should alert ” warned Professor Jérôme Salomon on March 27. Don’t wait until it gets worse. This symptom requires a teleconsultation or a call to 15.

Loss of taste and smell

Several ENT and French infectious disease specialists have noted the occurrence anosmias abrupt (loss of smell), often associated with ageusia (loss of taste) but without nasal obstruction, in suspected or confirmed COVID-19 patients. Often in people “rather young” according to Professor Jérôme Salomon, Director General of Health, and having forms “not very severe” of the disease. The coronavirus attacks cells of the central nervous system, that’s how it will disturb the taste and smell of the patient, said Professor Karine Lacombe.

What to do ? The National Syndicate of Physicians Specializing in ENT and Head and Neck Surgery (SNORL) recommends:

  • People with these symptoms should stay home and watch for other symptoms suggestive of COVID-19 (fever, cough, dyspnea). Call the attending physician if necessary. Do not self-medicate.
  • To the doctors of do not prescribe corticosteroids by general route or local in front of any clinical picture with acute anosmia or dysgeusia.

“In the current state of knowledge, it is not known if the nose washes are at risk of viral dissemination along the airways. It is therefore recommended not to prescribe, especially since these anosmias are not usually accompanied by a disabling nasal obstruction “ explain the experts.

What evolution? “According to the preliminary data we have, the natural course of acute anosmias linked to COVID-19 often seems favorable” believes SNORL

Digestive disorders: diarrhea …

Patients also report digestive disorders ((diarrhea, vomiting…). A US study published in March on coronavirus patients in China shows that out of 107 men and 97 women, aged 54.9 years on average, almost half (48.5%) went to hospital for digestive disorders such as diarrhea (29.3%), vomiting (8%) or abdominal pain (4%). These symptoms were most prevalent when subjects had a severe form of the infection. Among the subjects with digestive disorders, seven had no signs of respiratory impairment. In France, it is often the older patients who report digestive symptoms.

The WHO distinguishes several clinical syndromes associated with SARS-CoV-2: uncomplicated disease, mild pneumonia, severe pneumonia, ARDS (acute respiratory distress syndrome), sepsis and septic shock. In the most serious cases Covid-19, which require medical treatment: respiratory signs (difficulty breathing which can lead to acute respiratory distress syndrome that is, a failure in respiratory function).

In children: cough or shortness of breath associated with any of the following signs: cyanosis, acute respiratory distress (whining), signs of pneumonia with an alarm sign: unable to drink or breastfeed, loss of consciousness or seizures.

People most at risk of developing a serious form of coronavirus infection:

  • people aged 70 and over (even if patients between 50 and 70 should be monitored more closely);
  • patients with dialyzed chronic renal failure, NYHA III or IV stage heart failure
  • at least stage B cirrhosis
  • patients with a cardiovascular history (ATCD): arterial hypertension, ATCD of cerebrovascular accident or coronary artery disease, cardiac surgery;
  • insulin-dependent diabetics or with complications secondary to their pathology (micro or macro angiopathy);
  • chronic respiratory failure patients under oxygen therapy or asthma or cystic fibrosis or any chronic respiratory pathology likely to decompensate during a viral infection;

People with immunosuppression:

  • medicinal products: anti-cancer chemotherapy, immunosuppressant, biotherapy and / or corticotherapy at immunosuppressive dose,
  • uncontrolled HIV infection with CD4 <200 / min3
  • following a solid organ or hematopoietic stem cell transplant,
  • suffering from malignant hemopathy during treatment,
  • with metastasized cancer.

Pregnant women from the 3rd trimester

People with morbid obesity (body mass index> 40kg / m2 : by analogy with influenza A (H1N1)

As with many infectious diseases, people with co-morbidities, suffering from chronic diseases (hypertension, diabetes), the elderly (over 70 years), immunocompromised or frail are at higher risk. In more severe cases, the disease can lead to death.

Children and adolescents are much less often suffering from symptomatic forms: those under 10 years old represent 1% of cases, those between 10 and 19 years old 1% of the 72,314 Chinese cases described by Wu in a study published in the Jama February 24, 2020. This peculiarity is shared with MERS-CoV infection and influenza.

Two publications on Covid-19 relate to pregnant women. The one published in the Lancet concerns 9 women, aged 26 to 40, with documented SARS-CoV-2 infection in the third trimester of pregnancy and no comorbidity. It did not show any particular gravity of the infection at the end of pregnancy and of a transmission to the fetus. The other also concerns 9 pregnant women (including 1 twin pregnancy) and reports the absence of difference in the clinical presentation of the infection.

The length of time to heal Covid-19 is not really fixed. According to Dr. Gérald Kierzek, “after a fortnight when you have mild symptoms. Healing is spontaneous except when there is a severe form and you end up in intensive care where you need oxygen, where you have pneumonia and there we need to have medicine. Resuscitation patients stay in hospital for a long time, that’s more than 20 days. “

For Covid-19 patients who do not require hospitalization and which must therefore remain confined at home, the High Council of Public Health specifies the criteria for lifting containment, namely: disappearance of fever and possible dyspnea from the 8th day after the onset of symptoms. It is also recommended to wear a mask for 7 days after recovery from contact with a person at risk.

The peculiarity of the new coronavirus, in comparison to SARS, the Mers virus or that of the flu, is its strong 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. With SARS, 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 symptomsexplained Professor Arnaud Fontanet, epidemiologist at the Institut Pasteur during a round table in the Senate on February 26, 2020.

→ A more contagious virus than the flu: the transmissibility of SARS-CoV-2 is higher than that of seasonal influenza. The RO ((average number of people to whom a patient is at risk of transmitting the disease) is between 2 and 3, when it is only 1 for seasonal flu. The new coronavirus would be particularly very contagious because it is new and that the population French has never faced it.

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.

France should offer in the coming weeks serological tests for the presence of antibodies to Covid-19 in the blood. The objective is to assess the number of people who have been able to meet this virus and be immunized.

No treatment has proven its total effectiveness in combating SARS-CoV-2. Numerous clinical trials testing the efficacy of drugs against the coronavirus are in progress and listed by the WHO.

  • In mild forms of the disease that do not require hospitalization: in case of fever, it is advisable to take paracetamol and not anti-inflammatory drugs which can make the infection flare up. Watch for symptoms and if it gets worse with difficulty breathing, call 15.
  • To the hospital, For the treatment of patients with more serious forms, two drugs are used: “It’s about Remdesivir which had been developed for the Ebola hemorrhagic fever (and is reserved for severe forms in Covid-19 patients) and an even older drug, Ritonavir which is a anti HIV medicationindicated Catherine Leport, infectious disease specialist and member of the Coreb mission, on February 26 in the Senate.

Chloroquine: Plaquenil …

Chloroquine derivative, hydroxychloroquine has proven its effectiveness on 20 patients with coronavirus and followed by Pr Didier Raoult in Marseille. On March 26, this active substance found in the drug Plaquenil® (drug initially indicated for patients with chronic diseases such as lupus and rheumatoid arthritis) has been authorized for coronavirus patients, according to a decree published by Prime Minister Edouard Philippe and Minister of Health Olivier Véran. Her prescription, dispensation and administration can be done under the responsibility of a doctor in hospitals as well as for the continuation of the treatment of patients with severe forms home. The same goes for the Kaletra® medication ((lopinavir / ritonavir). The Medicines Agency, however, warned health professionals and patients about the heart risks associated with these treatments and recalled that should not be used in self-medication.

  • Discovery trial to test 4 combinations of drugs

A large trial called Discovery was also launched on March 22, 2020 on 3,200 Europeans affected by the coronavirus, including 800 French patients by Inserm, to analyze the effectiveness of five treatment formulas:

  • standard care
  • standard care plus remdesivir,
  • standard care plus lopinavir and ritonavir,
  • standard care plus lopinavir, ritonavir and beta interferon
  • standard care plus hydroxy-chloroquine.

Five French hospitals are participating at the start (Paris – Bichat-AP-HP hospital, Lille, Nantes, Strasbourg, Lyon) then other centers to arrive at at least twenty participating establishments. In China, around twenty clinical trials are underway to analyze the effectiveness of this molecule in patients infected with SARS-CoV-2. Hydroxycholoroquine (a chloroquine analog) used to treat rheumatoid arthritis and lupus is also the subject of two trials in China in COVID-19 disease. In addition, antibiotic therapy is used in the event of pneumonia.

The new coronavirus is transmits between humans mainly through saliva, droplets (cough, sneezing), through close contact with patients (handshakes …). It can also be transmitted through contaminated surfaces (coronaviruses survive up to 3 hours on inert dry surfaces and up to 6 days in a humid environment). Regular hand washing (approximately every hour) and wearing masks help reduce the spread of the virus. “To slow the spread of the virus in the population, we therefore need avoid any proximity or contact with others as much as possible, install a virtual barrier between individuals, scrupulously refer to the instructions for barrier gestures: confinement at home, respect for the distance between individuals, frequent hand washing with soap or hydro-alcoholic gel. It is the only way to date to fight individually against the progression of the epidemic. It is our duty to do so “, warns Dr Patrick Aubé, general practitioner.

Transmission via stool

As indicated by the High Council of Public Health in an Opinion delivered on March 5 “SARS-CoV-2 can be found in body fluids including stool. However, the infectious nature of the virus detected in the stool in some cases has not been proven and the risk of faecal transmission has not been documented” .

Animal transmission

There is currently no evidence that domestic animals such as dogs and cats can spread the virus and / or be infected by humans.

Water transmission : To date, no water contamination has been reported. “This disease is respiratory and probably animal to human, but the source has not yet been identified” explains the French government.

Covid-19 is a highly contagious disease. In the absence of truly effective treatments to counter it, prevention consists in respecting several barrier gestures.

• Vaccine: deadline, lines of work …

From the start of the coronavirus epidemic in France, researchers have been busy developing a vaccine against this highly contagious virus. According to the European Medicines Agency (EMA), such a vaccine should not not be available for at least a year. Among the avenues envisaged, producing a vaccine from that of measles or BCG (tuberculosis).

Covid-19 has high mortality in adults. 62% of people who died on March 31, 2020 had co-morbibidities and 90% were 65 years and older.

In March, theaverage age of deaths registered in France is 80.5 years and 59% of the certificates concern men.


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