The doubts about the coronavirus that solves the largest study on the outbreak

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How long would a coronavirus vaccine take? 0:28

(CNN) - An exhaustive study of more than 72,000 confirmed and suspected cases of the new coronavirus by Chinese scientists has revealed new information about the deadly infection that has arrested much of the country.

WATCH: Minute by minute: Beijing expels journalists from The Wall Street Journal for opinion piece about coronavirus

Conducted by a group of experts at the Chinese Centers for Disease Control and Prevention and published in the Chinese Journal of Epidemiology on Monday, the study is the largest and most comprehensive examination of coronavirus cases so far.

The study found that the new coronavirus is more contagious than the related viruses that cause SARS and MERS. While the resulting disease, COVID-19, is not as fatal on a case-by-case basis, its greater spread has already caused more deaths than its related coronaviruses.

The new study examined data from 72,314 patients, 44,672 of whom were confirmed cases of the virus (61.8%), along with 10,567 clinically diagnosed cases (14.6%) and 16,186 suspected cases (22.4%). Another 889 cases examined did not show any symptoms.

"Clinically diagnosed cases" are patients who show all the symptoms of COVID-19 but have not been able to get tested or are believed to have false negative results.

These are his main findings:

How serious is the disease?

Tedros Adhanom Ghebreyesus, general director of the WHO, said that more than 80% of patients "have a mild illness and will recover."

“In approximately 14% of cases, the virus causes serious diseases, such as pneumonia and shortness of breath. And approximately 5% of patients have critical illnesses, such as respiratory failure, septic shock and multiorgan failure, ”he said.

“In 2% of reported cases, the virus is fatal and the risk of death increases as it ages. We see relatively few cases among children. More research is needed to understand why. ”

How deadly is the coronavirus?

Of the 44,672 confirmed cases, the Chinese CDC said there were 1,023 deaths, a crude death rate of 2.3%, which is in line with other studies and projections.

In comparison, SARS had a mortality rate of 9.6% during the 2003 outbreak, while MERS has a lethality of 35%. Seasonal influenza, which is highly contagious and affects tens of millions of people, has a mortality rate of about 0.1%, according to the most recent estimates from the Centers for Disease Control in the USA. UU.

International experts have warned that the first numbers may not tell the whole story. Lethality rates may decrease as officials discover milder cases that do not seek medical attention.

"My sense and that of many of my colleagues is that the maximum case mortality rate ... is less than 2%," Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told Jim Sciutto of CNN in this Tuesday. "What is probably not counted is a large number of people who are asymptomatic or minimally symptomatic, so the denominator of their equation is much larger."

WATCH: Minute by minute: Beijing expels journalists from The Wall Street Journal for opinion piece about coronavirus

“Therefore, I think that it is at the top is 2% and will probably decrease when the whole count is done at 1% or less. That remains considerable if one considers the possibility of dealing with a global pandemic, ”he added.

Because the COVID-19 virus has infected many more people than the viruses that caused SARS and MERS, the number of people who have died from it so far has already exceeded both viruses. The SARS outbreak claimed the lives of 774 people, while MERS has killed at least 828 people since 2012.

Even so, the flu has caused many more deaths than all these viruses combined, killing tens of thousands of people in the United States every year, due to its massive spread.

The last death toll of COVID-19 is more than 1,800, all but five of which occurred in mainland China, where the worst of the outbreak is centered.

Who does it affect the most?

Many of these deaths have been among older people with pre-existing conditions that make them more susceptible to serious diseases from viral infections.

The Chinese CDC study found that among patients 80 years of age or older, the crude death rate is 14.8%. Among people with pre-existing conditions, it was discovered that people with cardiovascular disease had the highest risk, with a mortality rate of 10.5%.

When will it be controlled?

The study is published when Chinese authorities praise what appears to be a turnaround in the fight against the virus. Outside the province of Hubei, the epicenter of the outbreak, the number of new cases reported has decreased in the last 14 days.

However, scientists previously warned about self-sufficient epidemics in Chinese cities, and both Beijing and Shanghai remain in strict closure to protect themselves against the spread of the virus.

While the number of new cases reported has been reduced in China and other countries, the World Health Organization (WHO) warned that the new data should be analyzed "cautiously."

“This trend must be interpreted with great caution. Trends may change as new populations are affected. It is too early to know if this reported decline will continue. Each scenario is still on the table, ”said Tedros Adhanom Ghebreyesus, general director of WHO. during a press conference on Monday.

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