Coronavirus: update on what we know about the pandemic - France 24

Paris (AFP)

Number of deaths to fear, modes of transmission, differences with the flu ... The point on what we know and what we do not know about the coronavirus pandemic, which plunged the world into an unprecedented health crisis.

- Who is most at risk?

Mortality increases markedly with age, and having a chronic disease (respiratory failure, heart disease, history of stroke, cancer ...) is a risk factor.

According to a large analysis published on February 24 by Chinese researchers in the American medical journal Jama, the average death rate is 2.3% (out of nearly 45,000 confirmed cases). But there are no deaths among children under the age of 10. Up to the age of 39, the mortality rate remains very low, at 0.2%, then drops to 0.4% in those in their forties, 1.3% in those aged 50-59, 3.6% in those aged 60- 69 years and 8% in the 70-79 age group.

People over the age of 80 are most at risk with a death rate of 14.8%.

In Italy, the country in the world where the number of deaths is now the highest, the average age of deaths is 79.5 years, according to the Higher Institute of Health (ISS).

Out of a sample of 2,003 dead, 707 were in the 70-79 age group, 852 were in the 80-89 age group and 198 were over 90, according to an ISS press release.

"Seventeen Covid-19 positive people under the age of 50 died. Five of these people were under the age of 40, all male, between the ages of 31 and 39 and with previous serious medical conditions," said the ISS.

The institute has listed a dozen of the most common pathologies found in deceased people, the most common of which are hypertension, diabetes or ischemic heart disease (a serious cardiac pathology). 48.5% of those who died suffered from 3 or more of these pathologies and 25.6% from 2 pathologies.

Only 0.8% of the people, three in total, had no pathology.

- How many deaths can we expect?

According to the February 24 study, the disease is mild in 80.9% of cases, "severe" in 13.8% of cases and "critical" in 4.7% of cases.

If one relates the number of deaths in the world to the total number of officially registered cases, Covid-19, a disease caused by the coronavirus, kills approximately 4% of the diagnosed patients, with disparities according to countries.

Conversely, out of 255,000 positive cases recorded in the world since the start of the pandemic, almost a third is already cured, according to the American University Johns Hopkins, which keeps a daily count.

The supposed death rate from the disease must be taken with tweezers as it is not known how many people have actually been infected. Since many patients seem to develop few or no symptoms, their number is likely to be greater than the cases detected, which would therefore lower this rate.

In addition, countries have very different testing policies and some do not systematically test all suspected cases.

If we take into account these undetected cases, "this probably gives a death rate around 1%," recently explained the American Anthony Fauci, director of the National Institute of Infectious Diseases, before the American Congress.

However, the danger of a disease does not only depend on the absolute death rate but also on its ability to spread more or less widely.

Even if only 1% of patients die, "it can make significant figures if 30% or 60% of a population are infected," said Dr. Simon Cauchemez, of the Institut Pasteur in Paris.

The other factor that can worsen mortality from Covid-19 is the congestion in hospitals due to a massive influx of cases, which has already happened in Italy. This complicates not only the management of patients with severe forms of Covid-19, but also everyone else.

- What transmission, what symptoms?

The virus is mainly transmitted by respiratory route and by physical contact. Transmission by respiratory route occurs in the droplets of saliva expelled by the patient, for example when he coughs. Scientists estimate that this requires a close contact distance (about one meter).

To avoid contagion, health authorities emphasize the importance of barrier measures: avoid shaking hands and kissing, washing hands frequently, coughing or sneezing in the crook of one's elbow or in a disposable handkerchief , wear a mask if you are sick ...

In addition, you can become infected by touching an infected object and then putting your hand to your face (eyes, nose, mouth ...)

A study published Tuesday in the American journal NEJM showed that the new coronavirus is detectable up to two to three days on plastic or stainless steel surfaces, and up to 24 hours on cardboard.

However, these maximum durations are only theoretical, since they are recorded under experimental conditions.

The most common symptoms "include respiratory problems, fever, cough, shortness of breath and difficulty breathing," says WHO. Each of these symptoms may however be more or less present depending on the case.

In recent days, doctors have observed that a coronavirus infection can be accompanied by a loss of taste and / or smell.

"In the most severe cases, the infection can lead to pneumonia, severe acute respiratory syndrome, kidney failure, and even death," according to the WHO.

There is no vaccine or medication and management is to treat the symptoms. However, some patients are administered antivirals or other experimental treatments, the effectiveness of which is being evaluated.

- What differences with the flu?

Despite close symptoms, it is wrong to think that the disease caused by the coronavirus is just a common flu.

First, everything shows that it is more deadly. "The flu has a mortality of 0.1%, and this disease is ten times more deadly," warned Anthony Fauci. The WHO estimates that the seasonal flu kills between 290,000 and 650,000 people worldwide each year.

In addition, experts fear that the severe forms of Covid-19 may affect a larger part of the population than those of the flu.

"The older we are, the more fragile we are, the more we are exposed to serious forms but this can also happen to relatively young people who do not have chronic pathologies", recently stressed N.2 of the French Ministry of Health, Prof. Jérôme Salomon.

According to a Chinese study - involving 1,099 patients - 41% of severe cases were between 15 and 49 years old and 31% between 50 and 64 years old (compared to 0.6% for those under 14 and 27% for those over 65) ).

Finally, the other difference is that "we are not protected" against Covid-19, according to Professor Salomon: there is "no vaccine, no treatment" and man is not naturally immune to this new virus, which his body has never encountered before.

© 2020 AFP