All you need to know about coronavirus infections

March 10, 2020

A virus, Covid-19 (formerly known as 2019-nCoV), the diseases are first observed in China in late December 2019. It belongs to a large family of viruses, the coronaviruses. Very common, they can cause a simple cold as well as a serious respiratory infection such as pneumonia, causing fatal epidemics as was the case with Sras or Mers and now with Covid-19. What you must remember about coronavirus infections.

What is a coronavirus?

Coronaviruses, which owe their name to the crown shape of the proteins that coat them, are part of a large family of viruses, some of which infect different animals, others humans. They are likely to cause a wide range of diseases. In humans, these diseases range from the common cold to a severe lung infection, responsible for acute respiratory distress.

Coronaviruses cause deadly epidemics

On the subject, two deadly epidemics have already occurred in the 21st century, involving emerging coronaviruses, hosted by animals and suddenly transmitted to humans:

SARS-CoV (2002-2003), or coronavirus causing severe acute respiratory syndrome (SARS), which appeared in China: more than 8,000 cases were identified in 30 countries and 774 people died (almost 10% mortality).MERS-CoV (2012-2013), or Middle East respiratory syndrome coronavirus, so called because it was first detected in Saudi Arabia. 1,589 cases and 567 deaths in 26 countries have been recorded (a death rate of around 30%).The third deadly epidemic is that linked to the Covid-19 coronavirus (formerly known as 2019-nCoV), which appeared in China in December 2019. The first cases identified are people who went to a local market in Wuhan, in the province of Hubei.

How are emerging coronaviruses transmitted?

Coronaviruses are of animal origin: one species (“reservoir”) harbors a virus without being sick and transmits it to another species, which then transmits it to humans. In the cases of SARS-CoV and MERS-CoV, the reservoir animal was the bat. As Inserm explains, “the virus is asymptomatic in this animal. An intermediate host is therefore necessary for the transmission of these viruses to humans: the masked palm civet for SARS-CoV, sold on the markets and consumed in southern China, and the dromedary for MERS-CoV. ”

As for the Covid-19, the tank could also be the bat. In early February, a team of Chinese researchers from the South China University of Agriculture estimated that the missing link could be the endangered pangolin, a small scale mammal. But caution is advised, pending a final confirmation. The virus is said to pass to humans via animal secretions, under specific conditions that have yet to be identified.

Human-to-human transmissionThe SARS-CoV coronavirus and MERS-CoV are transmitted not only from animals to humans but also from humans to humans. Human-to-human transmission is also proven for the Covid-19. The disease is transmitted by postlets (droplets of saliva) projected by coughing or sneezing. Close and prolonged contact is therefore necessary to transmit it (family, even hospital or boarding room) or to have had contact within 1 meter of the patient, in the absence of effective protective measures.

One of the most important transmission factors seems to be contact with unwashed hands. So-called “barrier” measures are therefore essential to limit the impact of the virus: wash your hands frequently with soap or hydro-alcoholic gel, sneeze or cough in your elbow, avoid touching your face (nose, eyes or mouth are possible entry points for the virus) and use disposable tissues. Inserm insists that objects (such as letters and cardboard) do not allow the virus to survive for a sufficient period of time.

What are the symptoms of Covid-19?

The most common symptoms of the virus are fever, fatigue, or a dry cough. Some people may also experience body aches, headaches, tightness or shortness of breath. These symptoms suggest an acute respiratory infection or radiologically detectable lung abnormalities. In more severe cases, the infection can cause “respiratory distress, acute renal failure, or even multiple organ failure that can lead to death,” said the Ministry of Health.

As a reminder: the disease remains mild in 80% of cases and the researchers estimate the overall mortality rate from the virus at around 3.2%. Some patients also have an asymptomatic form of the virus: they are carriers of the virus, but have no symptoms.

Is there a vaccine for Covid-19?

Vaccines against pneumonia, such as the pneumococcal vaccine and the Haemophilus influenzae type B (Hib) vaccine, unfortunately do not protect against the coronavirus. The Covid-19 is so new and specific that it is necessary to develop a vaccine of its own. Researchers are still working on its development. According to the Institut Pasteur in France, the vaccine, if found, would not be available until the fall of 2021.

Are there people at risk of developing a more severe form of the disease?

Available information suggests that the virus can cause symptoms similar to those of moderate flu, but also more severe symptoms. As with many infectious diseases, people with pre-existing chronic diseases (hypertension, cardiovascular disease, diabetes, liver disease, respiratory disease …) seem more likely to develop severe forms, as are the elderly and immunocompromised .

Patients with chronic obstructive pulmonary disease (COPD) are particularly vulnerable. Children under the age of fifteen are unlikely to trigger a severe form of coronavirus. A study published in the journal Jama at the end of February also indicates that men could be more affected by the virus.

How to treat an infection with the new coronavirus?

The treatment is said to be symptomatic (it aims to relieve symptoms): fever medication (antipyretics)… In severe forms, sick people can receive antibiotics when a bacterial co-infection is present, be put on respiratory assistance…

Drugs that have been proven to treat other diseases, including viral diseases, are currently being tested against the coronavirus. The idea of ​​a treatment with chloroquine, used against malaria, was put forward at the end of February by Professor Didier Raoult, director of the Mediterranean Infection Institute in Marseille. The latter is based on the work of three Chinese researchers published in the journal BioScience Trends and carried out on cells cultured in vitro. Tests and clinical trials involving infected patients have yet to be performed.

As for the development of a specific antiviral drug for Covid-19, research is underway, but it would take at least a year to create a new drug.

How many people are affected by Covid-19 in the world?

According to March 9 estimates, nearly 110,300 cases have been reported, 62,100 people have been cured and 3,840 people have died, mostly in China. A total of 96 countries on five continents are now affected by the epidemic. The most affected countries, excluding China, are Italy, Iran and South Korea. “Believing yourself safe from the disease would be a fatal mistake,” said Tedros Adhanom Ghebreyesus, director general of the World Health Organization.

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