Wuhan coronavirus mortality falls for the first time by 2% of those affected | Society

Experts attribute this decline to two main factors. “The first is that at the beginning of a new epidemic, serious cases are the first to attract attention, while the mild ones go unnoticed. This means that the mortality recorded in those first days is higher ”, explains Santiago Moreno, head of the infectious diseases service of the Ramón y Cajal Hospital (Madrid).

The second, predictably with a minor impact, is due to the fact that “as more information about the virus and the disease is available, even if there is no specific treatment, care for patients and life support measures can be improved, which improves survival, ”adds Moreno.

For Pere Godoy, president of the Spanish Society of Epidemiology (SEE), “the predictable thing is that this relative decline is maintained, although we are still far from reaching the peak of those affected and the figures will continue to grow in absolute terms significantly.” “We can expect cases to continue doubling every week for a while,” he predicts.

Luis Enjuanes, director of the coronavirus laboratory of the National Center for Biotechnology (CNB-CSIC), brings a third cause that could also be influencing, although it is a “process that acts more in the medium term”. “New viruses tend to reduce their mortality over time. The most virulent kill their host faster and therefore have less chance of transmission. With the less virulent, which allow an infected person to continue in one way or another making their life and expanding them, the opposite is true. Over time, the less virulent tend to prevail, ”he explains.

According to Enjuanes, “although this process is usually more noticeable in the medium term, which also occurs when a virus jumps species, as seen in the SARS and the MERS [síndromes respiratorios], is that it mutates very quickly to finish adapting to its new host and this can also simultaneously affect its attenuation. ” For Rinses, both processes are favored in this epidemic because “the number of transmissions is being very high”

These explanations clarify the different mortality rates registered so far according to the geographical area, the lower the farther away from the epicenter of the epidemic. In Wuhan, deaths are close to one in 20 patients, a ratio that is almost halved in the rest of the Chinese provinces, according to data provided by the authorities. Outside the country, on the other hand, WHO – which includes data from Taiwan as if it were a part of China – had only one deceased among 2,160 infected on Thursday night.

“With health services alert, the further you are from Wuhan, the more and better studies of epidemiological links are made before the arrival of any new case. This allows, as seen in Germany, to detect patients with mild or very mild symptoms that in Wuhan are surely not identified, ”explains Godoy.

This trend is also observed in the data offered by WHO on the percentage of those affected with severe respiratory insufficiencies, which have gone from 21.5% of the total last January 28 to 13.7% on Thursday after maintaining a sustained line down.

The head of emerging diseases and zoonoses of the WHO, Maria Van Kerkhove, already advanced on January 4, after the meeting of the executive council of the agency, that the “percentages [de mortalidad] they should be used with caution as it is expected that mortality will change over time. ”

Van Kerkhove said that in these early phases of the epidemic the real number of people affected is “unknown” given the impossibility of detecting all cases, especially the mildest ones. The detection of patients with fewer symptoms – which reduces the mortality rate by increasing the overall number of those affected – “increases as surveillance and diagnostic means increase,” he added.

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