Coronavirus: the thesis of aerial transmission supported by a new study
RESEARCH – In January, in the lead-up to the Covid-19 pandemic, an infected and asymptomatic passenger contaminated one-third of his poorly ventilated bus for a trip of less than an hour and a return. There is evidence that the coronavirus is most likely transmissible by air.
The theory that the virus is transmitted through the air that everyone breathes out and in, rather than just through the large droplets expelled by sneezing and coughing, has long been neglected by health authorities around the world. Until a turnaround was made this summer under pressure from many experts on respiratory viruses and an accumulation of studies on the presence of viral particles in micro-droplets in the air, ejected by the simple word.
In an article published this Tuesday, September 1 by the American medical journal Jama Internal Medicine, experts from the Chinese Centers for Disease Control describe having interviewed and tested passengers who were transported in two coaches to a Buddhist event in the city of Ningbo on January 19, during a 50-minute trip (with a return trip in the same two coaches). No one wore a mask. A person in his sixties, without symptoms, was most likely the index case, as he had had previous contact with people in Wuhan, where the epidemic began. She was sitting on the right side in a row in the middle of bus number 2, between two other passengers, the article says.
An air conditioning system in the bus that recirculates the air inside the vehicle.
A total of twenty-three of the sixty-eight passengers on this bus were contaminated. Conversely, no infection was found in the identical number one bus. Notably, the circle of infections was much wider than the few rows around the sexagenarian, with infected people at the front and back of the bus.
If the virus was only transmitted by large droplets, the circle would have been smaller, since these droplets usually fall within a perimeter of one or two meters. In addition, the index patient had no symptoms at the time of the trips, so he did not cough.
The air conditioning system of the bus recirculated the air inside the passenger compartment and did not renew it; this probably contributed to spreading the virus throughout the bus, the authors conclude. "This investigation suggests that in closed environments where air is recirculated, SARS-CoV-2 is a highly transmissible pathogen," they write. Their meticulous study, which includes a map of the bus with the position of each contaminated person, is in addition to others along the same lines, including the case of multiple contaminations between tables in a Canton restaurant, again probably due to a ventilation system that does not renew the indoor air.
La rédaction de LCI