- Covid-2019 killed 3,200 in three months, but not everyone is as vulnerable to the epidemic.
- If this new disease seems less severe than the last epidemics (Sras, Mers ...), it is more virulent on the elderly and / or already sick than on children and healthy people.
- However, the analyzes of these first trends remain cautious, as there is still little perspective and precise information on the profile of the sick and the deceased.
The toll of the coronavirus epidemic exceeded 3,200 deaths this Wednesday (at the time of publication of this article). A figure that changes every day. And that continues to worry around the world. But this virus, less severe than the last epidemics (SARS, SEA, Ebola ...) does not attack everyone in the same way.
80% of cases are mild
All the specialists call for the greatest vigilance. Because we only have fragmentary and evolving information on this new coronavirus, and a decline of only two months. What seems to be emerging is that this coronavirus remains little fatal: between 1% and 3% of patients on average die from it. It's ten times more than the seasonal flu. But less than previous epidemics linked to a coronavirus: 34.5% for the Seas (Middle East respiratory syndrome) and 9.6% for SARS (severe acute respiratory syndrome).
"We must remember that in 80% of cases, this coronavirus takes a mild form," reassures William Dab, doctor and former president of the Directorate General of Health. Another nuance: it is possible that a certain number of people are carriers of the virus, but without symptoms, or suffer from a simple cold which will not be diagnosed as a Covid-2019. In this case, there would actually be many more people infected ... and a lower death rate.
Older people more affected
The most complete analysis to date, published on February 17 by the Chinese authorities, then on February 24 in the American medical journal Jama , shows that the mortality rate increases markedly with age. In this study, out of nearly 45,000 confirmed cases, the average mortality rate is 2.3%. Up to the age of 39, the mortality rate remains very low, at 0.2%. Then it drops to 0.4% in the forties, 1.3% in the 50-59 age group, 3.6% in the 60-69 age group 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%. Outside of China, there are also many elderly people among the victims. In France, three of the four patients who died were over 80 (the fourth was over 60). "It seems, in the current state, that dangerousness increases with age, confirms Jean-Philippe Santoni, pulmonologist at the Fondation du souffle. With a marked worsening in subjects over the age of 60 and a much higher risk of death in subjects aged 80 and over. Which doesn't surprise researchers so much. In all epidemics, especially of influenza, the elderly are the most at risk, in particular because the immune defenses decrease with age. "These vulnerable people must know and respect the barrier measures, advises the pulmonologist. Wash your hands 5 to 6 times a day, do not see the grandchildren if they are sick or if they return from a risk area, avoid handshakes and hugs, ventilate their accommodation twice a year clean the door handles well. "
The most vulnerable patients
Another factor that plays into the equation: "The elderly are also the segment of the population where cardiovascular diseases, cancers and respiratory diseases are the most numerous", continues the pulmonologist. For William Bad, these profiles are broader: "cardiac patients, those undergoing immunosuppressive treatment in the event of cancer or AIDS, and patients with chronic obstructive pulmonary disease (COPD) are most at risk" . In fact, on Monday, the France BPCO association alerted the Minister of Health in a letter: “The Covid-19 will give priority to damage to COPD patients, simply because a respiratory defect is the first victim affected by respiratory disease. "
Other diseases can play a role: diabetes, asthma or hypertension increase the risks. If the mortality rate, still according to this Chinese study, reaches 7.3% in people with diabetes, 6% in patients with hypertension and 5.6% for those who suffer from cancer (5.6% ), it drops to 0.9% in healthy people.
Children less affected?
A specificity which seems to surprise doctors, however, is that few children are affected by this Covid-2019, and that the cases seem mild, for the moment at least. Again, according to Chinese analysis, only 1% concerned children under the age of 9.
"This is a notable epidemiological difference compared to the flu, which attacks people under 20 with sometimes significant complications, especially in infants," notes Jean-Philippe Santoni. Children may have more robust and more recently acquired immunity through contamination with other coronaviruses. Because this Covid-2019 is part of a large family of coronaviruses responsible for seasonal colds. Perhaps, too, the little ones are less tested for this new virus, because many of them go through winter with snot in their noses ...
A difference between men and women?
Some also believe that the virus attacks men more than women. While they represent 51.4% of the confirmed cases in this Chinese study, they account for almost two thirds of deaths (63.8%). Be careful, answers William Bad, who recalls that men are "more prone to cardiovascular diseases. "
For some observers, this slight difference could be linked to the fact that men smoke more than women (in some countries). Tobacco is also a risk factor. a Chinese study carried out on 1,099 patients indeed demonstrated that 12% of infected and smoking patients died or went through resuscitation, against 5% of non-smokers. An equally remarkable fragility for influenza or pneumonia ... Perhaps the most anxious smokers will see the opportunity to put out their last cigarette?
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