Coronavirus: mortality, age, contagion… what reveals the largest study on Covid-19

It is the largest study of the new coronavirus to date. The China Center for Disease Control and Prevention published an investigation in the Chinese Journal of Epidemiology into 72,314 confirmed, suspected, clinically diagnosed and asymptomatic cases of viral pneumonia reported on February 11. Here are the main conclusions of the Chinese report.

The elderly at risk

The disease is mild in 80.9% of cases, "serious" in 13.8% of cases and "critical" in 4.7% of cases. People over the age of 80 are most at risk, with a death rate of 14.8%. Patients already suffering from cardiovascular diseases are the most threatened by a fatal outcome, ahead of diabetics or people suffering from chronic respiratory diseases or hypertension.

There have been no deaths among children under the age of 10, even if at least two babies have been infected in their mother's womb. Up to the age of 39, the mortality rate remains very low, at 0.2%, then increases gradually with age. Men are more threatened than women by a fatal outcome (2.8% against 1.7%).

Heavy tribute of medical personnel

A total of 3,019 doctors and other medical personnel were contaminated, including 1,688 severely. Five died on February 11. Of the serious cases, 64% worked in hospitals in Wuhan, like ophthalmologist Li Wenliang, who was reprimanded by the police in December for raising the alarm. His death from the coronavirus earlier this month created a rage in China.

Highly contagious

The germ is highly contagious. "The new coronavirus has spread very quickly in just 30 days from one city to the whole country," said the study.

The Wuhan factor

Nearly 86% of those infected live in Wuhan or have gone to the city where the virus appeared on a market where live animals were sold. The city has been de facto in quarantine since January 23, as well as a large part of its province, Hubei, closing a total of 56 million inhabitants.

VIDEO. Surviving Wuhan: "It feels like a post-apocalyptic video game"

Slowdown in the number of new cases

The epidemic reached "a first peak" between January 24 and 26, just when authorities quarantined Wuhan. A “downward trend” has been emerging since February 11, with a slowdown in the number of new cases of contamination, particularly outside of Hubei.

On February 13, Chinese authorities expanded their definition of the disease to include cases "clinically diagnosed" by X-ray of the lungs, not just a laboratory test. This change resulted in a sharp increase in the number of deaths and contaminations.

The report suggests that the decision to cordon off Wuhan and its region has helped stem the tide of contagion.

"Rebound possible"

The virus spread as hundreds of millions of Chinese people traveled from the north to the south of the country on the occasion of Lunar New Year, the biggest holiday on the calendar. This long leave has been extended to reduce the risk of generalized contagion. But as people return home by train, bus or plane, there is a risk of a "possible rebound in the epidemic".

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The virus can also "adapt over time to become more virulent", warns the report, which calls on the medical profession to "remain vigilant".