Covid-19 disease (novel coronavirus)


JANUARY 9, 2020 - DISCOVERY OF A NOVEL CORONAVIRUS (SARS-CoV-2). This virus is responsible for the infectious respiratory disease called Covid-19.

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Updated on December 15, 2020, at 3:00 pm 

Since mid-August, the WHO* has been doing weekly updates with changes in the number of cases and the number of deaths from one week to the next one.

See all figures, everyday, on WHO website

The French public health agency Santé publique France** regularly updates key figures and the evolution of Covid-19 in France and around the world (in French). The national agency announces the number of Covid-19 confirmed cases (underestimated because only among people who have been tested), but also and especially people currently hospitalized including those in intensive care, the number of deaths, Covid-19 clusters under investigation, French departments in vulnerable situations, etc. 


This pneumonia is an infectious disease caused by a virus belonging to the coronavirus family, currently referred to as SARS-CoV-2. The reservoir of the virus is probably of animal origin, even if SARS-CoV-2 is very close to a virus detected in a bat, the animal at the origin of the transmission to humans has not yet been definitely identified. The hypothesis of the pangolin, a small mammal consumed in southern China, as an intermediate host between bats and humans has not been confirmed.


  • The duration of incubation is an average of 5 days, with extremes of 2 to 12 days. The onset of symptoms appears gradually over several days, unlike the flu which starts suddenly.
  • The first symptoms are not very specific: headache, muscle pain, fatigue/tiredness. Fever and respiratory signs occur secondarily, often two or three days after the first symptoms.
  • In the first descriptive studies from China, an average of one week elapsed between the onset of the first symptoms and admission to the hospital in the disease phase. At this stage, the symptoms combine fever, cough, chest pains and respiratory discomfort. The performance of a chest scanner almost always shows pneumonia affecting both lungs. Other clinical signs have been described since the first studies: signs of involvement of the central nervous system, expressed in particular in elderly people in the form of disorientation; loss of taste and/or smell, which occur in 30 to 50% of infected adults, with a predominance in women, is very predictive of the diagnosis of Covid-19.
  • The severity of clinical signs requires that approximately 20% of patients remain in hospital and 5% require admission to intensive care. The most serious forms are observed mainly in people who are vulnerable because of their age (over 70) or associated diseases, in particular obesity.
  • Specific observational studies (such as the one carried out on passengers on the Diamond Princess cruise ship) as well as modeling work have shown that the infection can be asymptomatic or paucisymptomatic (causing little or no clinical manifestations) in 30 to 60% of infected individuals, especially in young children (under 12).


Most of the initially described cases concerned people who had been to a market selling live animals. The leading hypothesis is therefore that the virus is a zoonosis (a disease transmitted by animals). Human-to-human transmission was established later and it is estimated that, in the absence of control and prevention measures, each patient infects between 2 and 3 people.

Transmission occurs mainly by air (droplets of postillions emitted during coughing efforts but also during speech) and passes through close contact (less than a meter) and lasting (at least 15 minutes) with a contagious individual. Smaller particles can also be emitted in the form of ‘aerosols’ during speech, which would explain why the virus can persist in suspension in the air, in an unventilated room (and justifies in these circumstances the wearing of a mask). Finally, the virus can retain infectivity for a few hours on inert surfaces from where it can be transported by hands, which justifies good hand hygiene.

How is it diagnosed?

There are two types of tests to break the transmission chains of the virus and control the evolution of the epidemic in France

  • Virological tests (RT-PCR) make it possible to determine whether a person is carrying the virus at the time of the test by means of a nasal or salivary sample.
  • Serological tests are used to find out if a person has developed an immune reaction after coming into contact with the virus.

Read the conditions to be tested on (in French)


Since the start of the epidemic and as of June 25, 2020, 41 RT-PCR tests and 80 serological tests have been evaluated by the national reference center (CNR Institut Pasteur and CNR associated laboratory of the Hospices Civils de Lyon). The reports of the evaluations carried out by the CNR have been communicated to the French health authorities, who are responsible for defining a validation methodology for these tests and for establishing a first list of validated in vitro diagnostic medical devices, based on the evaluations. of the CNR and the specifications of the High Authority for Health.

Read "Tests for the diagnosis of SARS-CoV-2 infections" (in French)

Precautions / Prevention

Barrier gestures are effective:

  • Wash your hands regularly (water + soap) or use a hydroalcoholic solution.
  • Cough or sneeze into the elbow, or into a tissue.
  • Avoid touching your face.
  • Use disposable tissues (and throw them in the trash after the first use).
  • Greet without shaking hands, without kissing.
  • Keep a distance of at least 1.5 meters with any contact person.
  • Good ventilation of the rooms

In the absence of treatment, the best protection for you and your loved ones is, at all times, compliance with barrier measures and physical distance. In addition, wear a mask when the distance of one meter cannot be respected.


Read information on  prevention and precautions the World health organisation website.


The treatments currently available against the coronavirus are detailed under "Treatments" on the government's website. Numerous vaccine projects are currently being developed and tested in clinical trials. Find out more about the vaccination strategy on the  government's website.

Find the opinions of the High Council for Public Health about coronavirus, particularly concerning therapeutic recommendations.

Instructions in France : “I have symptoms (cough, fever) that remind me of Covid-19: I stay at home, I avoid contact with others. I get in touch with my doctor who can offer me a consultation and a diagnostic test based on the symptoms I have.

If the symptoms worsen with breathing difficulties and signs of suffocation, I call the “SAMU-Center 15”; experts will decide what to do. (source in French”

Avoid contact with those around you. Do not go to your doctor or to the emergency room, to avoid any potential contamination. Limit travel to what is strictly necessary.

Some frequently asked questions (updated on June 25, 2020)

  • What is the animal reservoir?

A virus, 96% identical to SARS-CoV-2, has been identified in bats captured in China. The bat is therefore most likely the reservoir of the virus.

  • How is the virus transmitted from animals to humans?

It is likely that a mammal served as an intermediate host between the bat and man. This intermediate animal is not identified with certainty, but the pangolin is suspected.

  • Can the virus survive in the environment? And if so, for how long?

According to the available data, the survival of coronaviruses in the outdoor environment is only a few hours on dry inert surfaces. Standard hygiene measures (hand washing, surface cleaning) are effective. (Read also paragraph 'Transmission', above)
New studies* indicate a risk of transmission of the virus by airborne route, through microdroplets emitted during speech or bio-aerosols of viral particles in suspension, which can be increased in confined spaces.
* Source: K. A. Prather et al., Science 10.1126 / science.abc6197 (2020)

  • How long is the incubation?

The duration of incubation is an average of 5 to 6 days, with extremes of 2 to 12 days, which justifies the quarantine period of 14 days.

  • How is Covid-19 diagnosed in patients?

The diagnosis is suspected in front of signs of respiratory infection in a person returning from a place where the virus ​​circulates, in the 14 days preceding the symptoms onset, according to the case definition of Santé publique France.

  • What is the period of contagiousness?

Contagiousness begins on average 2 days before the onset of symptoms and up to 7-10 days after the onset of symptoms.

Coronavirus : toute l’actualité de l’Institut Pasteur sur COVID-19 - Institut Pasteur

All Covid-19 news from the Institut Pasteur



* To follow the latest news on the novel coronavirus, visit the World Health Organization website.

** To follow the evolution of current events in France, visit the website of the French Ministry in charge of health.

*** For the procedure to be followed in France, visit the Santé publique France website.

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