Corona-danger by Breathing low? Harvard researchers disassemble the Aerosol hypothesis

moves the Coronavirus (Sars-CoV-2) that causes the lung disease Covid-19, most effectively from person to person Through droplets, or so-called aerosols? The an

Corona-danger by Breathing low? Harvard researchers disassemble the Aerosol hypothesis

moves the Coronavirus (Sars-CoV-2) that causes the lung disease Covid-19, most effectively from person to person Through droplets, or so-called aerosols? The answer to this question depends on what protective measures to prevent a contagion of the best.

thought the beginning of the pandemic, virologists, that the pathogens get stuck in the large droplets that people Sneeze or cough, spinning out impregnating material. These are up to a Millimeter in size, and fall by gravity in a distance of two meters to the ground. You land on surfaces that can be transmit the virus by smear infection when someone touches contaminated objects and you move by Touching of the mouth, nose, or eyes, on mucous membranes.

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a few months Ago, the aerosols in the point of view of the researchers were, however. These tiny droplets less than five microns in diameter to emit people to Breathe, speak and sing. When the Infected fly, the worms with the fine moisture mist by the air and can hold, depending on the room ventilation and hours. In addition, experiments showed that the mixture of droplets and aerosols generated when Speaking and coughing, can be thrown up to eight meters wide.

Covid-19: Transmission by aerosols is considered to be largely safe

Since then, debate in science is whether the established measures – cough and Sneeze into the crook of your arm, wash often hands, Wear a mask and keep at least 1,5 meters distance of the Other – as a protection is sufficient. Least, some 240 experts from 32 Nations have demanded in an open letter to the health authorities and the world health organization, the Transmission by aerosols to recognize the protection recommendations accordingly.

Since then, everyday masks would not be enough, because aerosols penetrate them, or you can fly around. Also, plastic visors offer because of the gap between the shield and face equally full of protection as the recommended distance.

Now a group of researchers come to another conclusion

Now a group of researchers comes to the infection Michael Klompas of Harvard Medical School in a study published in the "Journal of the American Medical Association," lied to a different conclusion: That Speak and cough aerosols caused, and that it was able to demonstrate Sars-CoV-2 in samples of air, is no proof that aerosols connect. "In spite of the experimental data, the infection rates in the population, and to arrange the Transfer within groups difficult to do with a aerosol-based contamination over larger distances," the authors write.

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As a further Argument Klompas and his colleagues cite the reproduction number of the Sars-CoV-2, which indicates how many additional people infected, an infected Person during the pandemic. Before protection came in force, they amounted to about 2.5. "This is more of the flu as viruses which are spread known over-the-air, such as measles, with a reproduction number of 18", - stated in the study. "Either for an infection, the necessary amount of Sars-CoV-2 is much larger than in the case of measles, or aerosols are not the dominant mode of Transmission."

What is against aerosols is the main route of transmission of Sars-CoV-2

Also speaks to the contagion rates of medical personnel unknowingly Covid-19-treated patients, were low, previous studies suggest that your share spent more in less than three percent, according to the researchers. In addition, the Virus about to go in series with close contacts between Patients only five per cent of the contact persons. This would not, however, infected in the same way, the contagion depends rather on the intensity and duration of the contact. The greatest risk is for members of a household with a transfer rate of ten percent to 40 percent.

The authors mention other points, the aerosols as the preferred mode of Transmission of Sars-CoV-2 speak: To produce droplets of Infected may be constant, and aerosols, but most of these secretions to infect anyone. The speak more for the secretions of the traps quickly and within a small Radius from the Diseased to the ground, as for virus-Laden aerosols, the hours by air wabern.

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In their analysis, the researchers also go on the main argument for an aerosol-based contagion: The always clenched occurring infections in choirs, Restaurants or large offices. Measured in terms of the reproduction number of the Sars-CoV-2, these events are the exception rather than the rule.

It also experiments with so-called phage point: you show that such viruses, which infect bacteria, can spread from a single contaminated doorknob from inside of seven hours in a whole office building. Viruses, they would therefore have to be not transmissible by air, in order to spread rapidly.

"Need to compare effectiveness of different respiratory protection equipment,"

These reservations are of course speculative and is not locking the Transmission over the air, confess Klompas and his colleagues – in particular, if many people in poorly ventilated spaces were. Then could accumulate otherwise, not significant quantities of virus Laden aerosols and lead to a contagion. Your approach will deliver but an alternative explanation for the observed clusters of infections, according to the authors.

they also call a Test that could help determine the most important route of Transmission of Sars-CoV-2: You have to compare the efficiency of different respiratory protective equipment. It would be transferred mostly through the air, would have disposable protect respiratory masks type N95, the filter out at least 95 percent of all aerosols better than a simple medical mask. A recently published meta-analysis actually came to this conclusion, but based on a strong methodological shortcomings, criticize Klompas and colleagues. Four further studies compared the N95 masks directly with medical masks, would have found no difference.

1.5 meters distance, and high-quality mouth-nose masks are the best protection

Even if the Transmission of Sars-CoV-2 was not yet understood and there is no perfect experimental data, which clearly speak for one or the other mode of Transmission, the existing evidence appears, however, inconsistent with an aerosol-based Transmission, especially in a well-ventilated area, sum Klompas and his colleagues. Practically, the hot, 1.5 meters distance, and the Wearing of high-quality, mouth-nose masks should be sufficient to minimize the spread of the pathogen.

An anecdote-based report from the village of Springfield in the US state of Missouri this view. There are two unknowingly with the pathogen-infected hairdressers had to cut a total of 139 clients hair before they learned of their infection. They worked in a sophisticated System, with masks, wearing both the hair artist as well as their customers, and arranged their chairs, with large intervals, in addition, well-timed appointments should minimize contacts between customers.

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Actually, no customer to put, such as the Springfield-Greene County Health Department announced. The authority imposed on all the Affected a two-week quarantine and tested also 67 of them, each with a negative result. Although asymptomatic cases are among the non-tested persons, the "exciting news about the value of masks to infection with Covid-avoid 19," stresses head of Clay Goddard. "The result supports the Wearing of masks in public places, especially as the distance is not possible to keep." The spread of the pandemic could be brakes. Corona-immunity could only stop for a minute – researchers find new information FOCUS Online/Wochit Corona-immunity could only stop for a minute – researchers find new evidence temperatures soar to the top: the Azores brings up the long-awaited summer PCP temperatures soar to the top: the Azores brings up the long-awaited summer

Updated Date: 22 July 2020, 08:27

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