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Covid, it is already an established fact, is in the air.
Like other infectious diseases such as measles, chickenpox or tuberculosis, it is transmitted through aerosols that can remain in the air for long periods of time and long distances. The quality of the virus in the air is identified through public health authorities, the World Health Organization added. (WHO) and the Centers for Disease Control and Prevention (CDC).
However, when the virus appeared, and for some time afterwards, the public health government thought that the virus could spread through giant droplets that, unlike aerosols, can only measure about two meters and can fall on nearby surfaces, which in turn become potential cars for transmission. It was the theory that everyone was cleaning up their purchases and wondering if they deserved to disinfect their mail in early 2020.
Although aerosols and droplets may look similar, their implications for the public fitness are very different. Speculation that covid has spread through droplets has informed public fitness recommendations, such as the emphasis on the importance of social distancing, dressed in any type of mask, adding cloth ones and disinfecting surfaces, to focus on high-quality masks that can prevent aerosol transmission (such as N95) and ventilation.
But evidence that covid in the air abounded at first, which lacked the will to settle for it. The WHO called the theory of airborne transmission disinformation and tried to dispel it by sharing it on its social media channels: “#HECHO: #COVID19 is NOT up in the air. “
However, as early as April 2020, a team of scientists presented THE WHO with evidence of aerosol transmission of covid, collected by reading the transmission dynamics of certain superpropagation events. “I said well, let’s go to them, and then we’re going to have a moderate debate as scientists,” said Jose Jimenez, a chemistry professor at the University of Colorado at Boulder, who was part of the team led through famous atmospheric researchers. physics Lidia Morawska. ” But they were completely closed and rude, and they yelled at Lidia,” he said. It took the WHO nearly two more years to recognize that Morawska was right all along.
Jimenez, who had never worked on infectious diseases before, was shocked. But his colleagues don’t: The reaction they won is related to a centuries-old history of public opposition to the concept of aerosol transmission, which Jimenez set out to study for a paper published this week in the International Journal of Indoor Environment and Health.
For most of human history, the concept that the disease would spread through the air is far from controversial. From the miasma of Hippocrates to the Persian physician Ibn Sina (Avicenna), early theories about disease transmission referred to confusing concepts of harmful smoke from environments unhealthy to people.
It was only in part of the seventeenth century that the discovery of bacteria and microorganisms made it possible to perceive that the disease can also spread from one user to another. What followed, the article says, was a long debate between the so-called “contagionists” who believed that diseases were transmitted from one user to another, and the “miasmatics” who believed in airborne contagion. , an American epidemiologist.
Chaplin’s experiments showed that germs can be transmitted simply through direct contact, but he found that persistent reliance on exclusively airborne transmission is an impediment to controlling diseases that spread through contact. making a great effort to protect against contact infection? [. . . ] It is impossible, as I know from experience, to teach other people to avoid contact infection when they are firmly convinced that air is the main vector of infection,” he wrote in 1914 in the Journal of the American Medical Association (JAMA).
With more accumulated wisdom about the vectors of diseases such as cholera (water) or malaria (parasites), Chaplin after all came to the conclusion that airborne transmission was the most unlikely in peak scenarios. As Jimenez and his colleagues said in the paper, he turned the lack of evidence of airborne transmission into evidence of its absence. In his writings, the newspaper reports, Chaplin advocated “rejecting airborne transmission as ongoing speculation and devoting our number one attention to the prevention of contact infections. “he saw the paradigm shift as a historic step and equated the concept of aerial transmission with little more than folklore. race since the time of Hippocrates,” he writes.
The result was an overcorrection, driven through the so-called reformers who followed Chaplin’s new paradigm. “They showed that miasma is wrong, and then they said, it’s not us, it’s superstition, it’s anything we have to overcome,” Jimenez said.
The rejection of aerosol transmission as superstition had a strong emotional rhythm that is still felt today. To the transmission of the disease without direct contact, preference has been given to the theory that pathogens are transported through larger droplets, of the same type in the first place accused. of spreading covid.
In fact, covid is not the first case in which scientists have had to fight to admit aerosol transmission. Droplets were first thought to be the cause of non-contact transmission of tuberculosis, measles and smallpox, and it was only later. irrefutable evidence that the clinical status quo would support aerosol transmission lifestyles.
“Something we were told at the WHO assembly is, ‘covid [] is not airborne like measles, if it’s like measles, we would notice. ‘But in fact, measles and chickenpox, which are highly contagious airborne diseases, were described as droplet-shaped diseases until the 1980s,” Jimenez said.
In addition, he said, while a lot of effort is put into testing each case of aerosol transmission, due attention is not paid to the fact that droplet transmission lacks really extensive evidence. “Droplet transmission, what we’ve been told and they keep telling us is the main mode of transmission [covid], this has never been directly proven, not just for covid, but for any disease in the history of medicine,” Jimenez said.
Aerosol scientists argue that there is a false physical impression in the very theory of droplet transmission, but resistance from the public health government remains strong. “Over the past two years, there have been significant conversations about the modes of transmission of COVID-19, namely how SARS-CoV-2 is transmitted through the air. [. . . ] This is a cross-sectional factor that affects not only SARS-CoV-2, but also other respiratory pathogens capable of causing a public health emergency of foreigners. concern,” reads a message shared with Quartz through WHO spokeswoman Margaret Ann Harris. “Lately, WHO is leading and coordinating an international technical consultation procedure to discuss and reach consensus on this factor with global experts. “
Admitting airborne transmission has implications that go beyond infectious medicine or malicious beliefs. If a disease is transmitted by direct contact or proximity, the duty to prevent it may fall on the individual. Protective equipment, distancing, disinfection – these are all measures that other people can take to prevent epidemics. In this way, being in poor health becomes a private failure: other people have not washed their hands or taken certain precautions.
But if the virus is airborne and one is inflamed in a school or office, where air quality cannot be measured, then the failure cannot be personal. Similarly, larger droplets can be stopped through any face covering, but if certain types of mask (such as N95 respirators), then there is greater institutional involvement to make sure they are affordable, available, and meet certain quality criteria. “The establishments (the CDC, the government, the WHO) persist in ambiguity because it is very convenient,” Jimenez said.