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The main transmission method of the COVID-19, infection caused by SARS-CoV-2 coronavirus, it is through respiratory droplets (droplet) that we expel when we cough, sneeze, speak, sing and even when we simply breathe. However, recent research has shown that air transmission through aerosol may play a role in the spread of the pathogen, so much so that it has prompted the Centers for Disease Control and Prevention (Centers for Disease Control and Prevention – Centers for Disease Control and Prevention) to modify the guidelines dedicated to the management of pandemic. A new study seems to widely support the airborne scenario, to the point of making the concept of “close contact“At risk (all those who are within 2 meters of a positive for at least 15 minutes). Suffice it to say that according to the new research, a girl became infected after just 5 minutes of exposure and more than 20 feet from the “source.” The contagion occurred in a closed room (a restaurant) due to the Air flow released by a conditioner.
The study leader was a South Korean research team led by scientists from the Jeonbuk National University School of Medicine, who collaborated closely with colleagues from the Jeonbuk Center for Infectious Disease Control and Prevention, the Korean Agency for disease control and prevention and other institutes. The scientists, led by Professor Ju-Hyung Lee, an infectious disease expert from the Department of Preventive Medicine at the University of South Korea, reached their conclusions after analyzing in detail what happened in a Jeonju restaurant, where some customers were infected. with the SARS-CoV-2 coronavirus by a visitor from out of town. Jeonju’s case was quite significant for the epidemiology Since there had been no cases in the city for two months, a high school girl who had not left the area in weeks tested positive.
Thanks to the sophisticated (and controversial) system of contact tracking developed by the South Korean CDC, thanks to which it is possible to detect displacements people in just 10 minutes thanks to mobile phone GPS data and the use of credit card, it was discovered that the girl had been in “contact” with a positive – a door-to-door saleswoman – for only 5 minutes inside the restaurant. In reality, the contact between the two women was nothing short of fleeting. From research by Lee and colleagues, also based on data collected through interviews, images of CCTV cameras and location of mobile phones, it was determined that they never spoke, did not touch the same cutlery, the same doorknobs and the like. They also sat 6.5 meters apart. Despite this, the girl (as well as two other restaurant patrons) was still infected. How is it possible?
Thanks to the support of an engineer specialized in aerodynamics, scientists have identified the carrier of the infection in a air conditioning, the flow of which was coming from the ceiling, hit the positive woman and hit several people along the way, including the student. According to scientists, the girl was affected by a significant dose of viral particles, which traveled 1.2 meters per second. The aerosol droplets were likely larger than 50 microns, as specified by Virginia Tech professor Linsey Marr for the Los Angeles Times. Other clients of the restaurant, closer to the positive woman but with the flow of air behind them, did not become infected, as shown in the graphs that you can see below. According to the American expert, “eating in a restaurant is one of the riskiest things to do during a pandemic,” because “even if there is a distance, as this and other studies show, it is not enough.” However, it should be noted that the Jeonju headquarters had no windows is a ventilation system (beyond the air conditioner) to adequately transmit air flows and above all promote their exchange. So other places are undoubtedly safer.
However, since in some circumstances infection can occur in a very short period of time and even at distances much greater than safe, if there is direct airflow over an infected person, Lee and his colleagues emphasize that for him the Control of this highly contagious disease requires updated guidelines including prevention, contact tracing, and quarantine for COVID-19, as outlined in the study summary. The article “Evidence for long-distance droplet transmission of SARS-CoV-2 by direct airflow in a restaurant in Korea” was published in the Journal of Korean Medical Science (JKMS).
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