who are the most vulnerable people?

Better to be young and healthy than old and sick, according to a Lapalissade of circumstance. The coronavirus kills more people in the elderly, or already suffering from serious or chronic illnesses, and the epidemic has more deaths in men than women.

Since its appearance in China in December, respiratory infection Covid-19 has resulted in more than 2,800 deaths out of 83,000 infected people in at least 53 countries. In the majority of cases, it results in symptoms mild or moderate (cough, fever, fatigue …), but in the most severe cases, patients may enter into severe acute respiratory distress or be victims of renal failure acute, or even failure of several organs, which can lead to death. Its average mortality rate remains relatively low; it is not yet known with precision, but it is estimated between 1% and a little more than 3%.

It’s much more than influenza seasonal (around 0.1%) but less than previous epidemics linked to a coronavirus, much more virulent: 34.5% for the Seas (syndrome Middle East) and 9.6% for SARS (severe acute respiratory syndrome), of which the virus is close to 80% of the new coronavirus.

Mortality rate increases with age

Certain categories of the population are however clearly at higher risk, according to the available data. The analysis the most complete to date, published on February 17 by the Chinese authorities, then on February 24 in the American medical journal Jama, thus shows that the mortality rate increases markedly with age.

Out of nearly 45,000 confirmed cases, the average mortality rate is 2.3%. 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 increases to 0.4% in those in their forties, 1.3% in those aged 50-59, 3.6% in those aged 60-69 and 8% in those aged 70-79. People over the age of 80 are most at risk with a mortality rate of 14.8%. Outside of China, there are also many elderly people among the victims. In Italy, the most affected country in Europe, at least six people among the first 14 deaths were aged 80 or over.

Young children are spared

The absence of victims among the youngest leaves experts perplexed, since infants and young children are usually among those vulnerable to infectious diseases. " This is surprising because, when we look at all the other respiratory infections – bacterial or viral – we almost always have a lot of serious cases in the very elderly, but also in the very young, especially those under five. ", Underlines Cécile Viboud, epidemiologist at National Institutes of Health (United States).

" We must look to see if there is not a form of cross protection because of the recent epidemic seasonal coronaviruses, those that cause simple cold ", observes John M. Nicholls, professor of pathology at the University of Hong Kong. A second hypothesis is that the immune system children would be conceived " so as not to overreact in the presence of new infectious agents ".

Another notable characteristic of Covid-19 is that men are more threatened than women by a fatal outcome: while they represent 51.4% of the cases confirmed in this study, they account for almost two-thirds of deaths (63, 8%).

Serious or chronic illnesses, tobacco are aggravating factors

This could be explained " at least in part »By the higher proportion of smokers among men, points Cécile Viboud, tobacco being among the parameters that increase the risk of death. Differences in behavior or immune response are also advanced as hypotheses. Chinese statistical data also give indications of other risk factors possible, including having a chronic illness.

The mortality rate thus climbs to 6.3% in patients with respiratory disease (respiratory failure, asthma, chronic obstructive pulmonary disease …). It is even 10.5% in those with heart disease ((heart failure, history ofStroke or infarction …) and 7.3% in people diabetics.

Patients withhypertension (6%) or one Cancer (5.6%) also have a higher mortality rate, while it drops to 0.9% in healthy people. These profiles are found among victims from other countries. Thus, in Italy, among the first 14 victims, one was hospitalized for cancer, another had a infarction a few days earlier, a third suffered from heart conditions and was on dialysis, and at least two others had serious illnesses.

Young practitioners, victims of their inexperience?

If the overall mortality of infected Chinese health professionals remains low, in the published figures (0.3%), the young age of several of them strikes, because it comes out of the typical profile of other victims. David N. Fisman, an epidemiologist at the University of Toronto, says that young caregivers are more likely to be in direct contact with the sick than older people. John M. Nicholls also puts forward a probable " lack of experience and training (at) take care of patients contagious " and to use protective equipment correctly, when they are overwhelmed by the influx of patients and the previous comparable situation, the SARS epidemic, dates from 17 years ago.

As with other infectious diseases such as the flu, people who do not have risk factors should not feel exempt from precautionary measures recommended (frequent hand washing, cough in your sleeve, etc.). These “barrier measures” in fact avoid transmitting the virus to more fragile people, who are likely to develop a severe or even critical form of the disease.

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