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In January, at the start of the covid-19 pandemic, an infected and asymptomatic passenger infected a third of his poorly ventilated bus, during a trip of less than an hour, indicating that the coronavirus is transmittable by air.
The thesis of the transmission of the virus in the air, that everyone exhales and inhales, instead of the large droplets expelled by sneezing and coughing, was initially neglected by health authorities around the world, before a radical change this summer before pressure from many respiratory virus experts. and an accumulation of studies on the presence of viral particles in microdroplets in the air exhaled by mere speech.
In an article published Tuesday by the American medical journal “Jama Internal Medicine”, experts from the Chinese Centers for Disease Control describe questioning and examining passengers who were transported by two buses to a Buddhist event in Ningbo city, the January 19, in a 50-minute trip (with return in the same vehicles). Nobody wore a mask.
A 60-year-old, without symptoms, was probably the initial case, having had previous contacts with people from Wuhan, where the epidemic began. He was traveling sitting on the right side, in the middle of vehicle 2, between two passengers. In total, 23 other passengers in this car were contaminated, among 68 people. On the contrary, no infections were registered in the identical car number 1.
The circle of infections was much wider than the queues around the 60-year-old man, with infected people in the front and back of the bus: if the virus were transmitted only in large droplets, the circle would have been smaller, since they generally fall within a perimeter of one to two meters. On the other hand, the initial patient did not present symptoms at the time of the trip, so he did not cough.
The car’s air conditioning system recirculated the air inside the vehicle and did not renew it, which likely contributed to the spread of the virus, the research authors concluded. “This survey suggests that, in closed environments where air recirculates, SARS-CoV-2 is a highly communicable disease,” they wrote.
The detailed study, which includes a plan of the vehicle with the position of each infected person, joins others in the same direction, specifically the case of multiple contamination between tables in a restaurant in Guangzhou, probably powered by a ventilation system that does not renew indoor air.
The coronavirus pandemic that causes covid-19 has already caused at least 851,071 deaths and infected more than 25.5 million people in 196 countries and territories, according to a report by the French agency AFP.
