Science

“It is not worth disinfecting surfaces in the household”

Ten days, twelve days, fourteen days – how long should the doubling time be so that the current coronavirus measures can be relaxed? Politics are currently changing their minds more often, and Charité chief virologist Christian Drosten cannot give a definite number in his daily NDR podcast.

“There are no general rules here,” says Drosten. The time in which the number of infections is doubled is currently around twelve days in Germany. Such a number provides information about how many patients have to be admitted to the hospital and how this could burden intensive care medicine, according to Drosten.

Disinfection of surfaces only necessary in the hospital

It is the task of a central institute such as the Robert Koch Institute to closely follow these numbers. In a statement by the National Academy of Sciences Leopoldina, Drosten, together with other scientists, made recommendations as to which measures are now important to further contain the virus.

This includes more tests and use mobile data to track contacts of infected people faster, above all one thing: the consistent wearing of a mask. What does not help in the fight against the virus, however, is the disinfection of surfaces in the household. “It is not worthwhile to treat all possible surfaces with disinfectant in the household,” Drosten later said in the podcast. He was “almost certain” of that. It is different in the hospital, where it is also about the patient's body fluids.

In general, the risk of infection via surfaces is not particularly high, the current anti-coronavirus measures are therefore intended to transmit air and droplets exclude. Mask wear could be difficult to enforce in Germany, however, says Drosten. “We do not have the best starting conditions in our company to have all masks worn.”

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It there is no cultural anchorage, and there are currently no masks available. Nevertheless, it is important that everyone wears masks to protect others. In the podcast, Drosten refers to new studies that provide evidence of third-party protection by wearing simple mouth-nose masks.

A Hong Kong study published last Friday in Nature magazine examines a large group of adults with upper respiratory tract infections, i.e. throat and nose. The study was conducted before the advent of Sars-2, and the patients had normal cold coronaviruses, the influenza virus, and rhinoviruses, which are rhinitis viruses.

Mouth and nose masks protect others

30 minutes the air around the patient's head was sucked out , collected and preserved so that it can be examined in the laboratory. Both larger droplets falling to the ground and very fine droplets floating in the air, the so-called aerosol, were collected.

The results are clear, says Drosten: Eleven patients the study were corona infected and wore a mouth and nose mask. “In none of the eleven patients a virus could later be detected from the device.” In a group without a mask, however, larger and smaller droplets were found in ten patients.

Another study with Covid – 19 – Patients from Singapore give reason to suspect that the disease can also be transmitted through the air. In two of three patients, droplets from the ambient air were detected in this study, both small and large.

Infection cannot be prevented with a mask

Especially in dry, warm room air, droplets dry quickly, become smaller and stay in the air longer, explains Drosten. But there is no reason to panic: In many rooms, such as supermarkets, the air would be circulated by ventilation and air conditioning systems, which would make airborne contamination less likely. It is also a fact that wearing a simple mask cannot prevent infection by fine droplets in the air.

Another interesting observation of the study from Singapore: wipe samples of surfaces from the rooms of the infected patients were only in the first week of the Disease positive for the virus. The trickle of the virus stops after a week, explains Drosten, even though the patients were still ill.

In the end there was a symptom of the coronavirus infection: the sudden loss of taste and smell. A survey of scientists from Iran with more than 15. 000 Participants found that this could be a common symptom of a Sars 2 infection. “If I suddenly didn't have enough in my everyday life, I would stay at home first,” says the virologist.

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