Covid, it is now an established fact, is Hawaii.
Like other infectious diseases such as measles, chickenpox or tuberculosis, it is spread through aerosols that can remain in the air for long periods of time and travel long distances. The airborne quality of the virus is recognized by public health authorities, including the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).
Yet when the virus emerged, and for some time after, public health officials thought the virus might have spread through large droplets, which, unlike aerosols, could travel only two meters, and fell on nearby surfaces. , which in turn become potential vehicles. transmission. It was this theory that got everyone wiping out their groceries and wondering whether or not to disinfect their mail in early 2020.
Although aerosols and droplets may sound alike, their public health implications are very different. The notion that COVID was spread by droplets informs public health advice such as emphasizing the importance of social distancing, wearing any type of mask, including clothing, and disinfecting surfaces – a focus on high-quality masks As opposed to which can prevent aerosol transmission (such as N95s) and ventilation.
But evidence that COVID was in the air was quickly abundant – the will to admit it was lacking. WHO labeled the theory of air transmission as misinformation, and worked to overcome it, shared on its social media channel: “#FACT: #COVID19 is not spread by air.”
Yet in early April 2020, a team of scientists studying the transmission dynamics of some superspreader events presented evidence of aerosol transmission of COVID-19 to the WHO. “I’m right, we’ll explain them, and then we as scientists will have a fair debate,” said Jose Jimenez, a professor of chemistry at the University of Colorado, Boulder, who was on the team led by renowned atmospheric physicist Lydia. Moravska. But the WHO team, he said, was closed to the idea, and one of them was even rude and yelled at Moravska. It took almost two more years for the WHO to admit that she was absolutely right.
Jimenez, who had never worked on infectious disease before, was perplexed. But his colleagues weren’t: the reaction he met with a century-old history of public health opposition to the idea of aerosol transmission was what Jimenez set out to research for a paper published this week in the International Journal of Indoor Science. It was published in Environment and Health.
from myasma to contact infection
For most of human history, the idea that disease would travel through the air was far from controversial. From the Myasma of Hippocrates to the Persian physician Ibn Sina (Avicenna), the first theories of how disease spread included vague concepts of bad smoke floating in people from unsanitary environments.
The discovery of bacteria and microorganisms by the late 17th century led to the understanding that disease could be transmitted from person to person. What happened, the paper explains, was a longstanding debate between so-called “infectionists” who thought diseases spread from person to person, and “mysmatists” who believed in contagion through the air. Later discoveries, including germ theory, were in one camp or another by the turn of the century and in the work of Charles Chapin, an American epidemiologist.
Chapin’s research showed that germs could be transmitted through direct contact, but he found that persistent belief in airborne transmission in particular was a deterrent in preventing diseases spread by contact infection. “If the sick room is full of floating contaminants, what is the use of putting great effort into preventing contact infection? […] It is impossible, as I know from experience, to teach people to avoid contact infection while they are firmly convinced that air is the main vehicle of infection,” he wrote in his 1910 book, Sources and methods of infection,
With more knowledge about the vehicles of diseases such as cholera (water) or malaria (mosquitoes), Chapin eventually came to the conclusion that air transmission was most likely in most scenarios. As Jiménez and his colleagues put it in the paper, they turned the absence of evidence of airborne transmission into evidence of its absence. In his writing, the paper reports, Chapin advocates “abandoning airborne transmission as a working hypothesis and devoting our main focus to the prevention of contact infection.” He saw the paradigm shift as a historic step, and described the idea of aerial broadcasting as little more than folklore. “It would be a great relief to most people to be free from the ghost of infected air, a ghost that has followed the race since the time of Hippocrates,” he wrote.
This resulted in an overreform led by the so-called reformers, who adopted Chapin’s new paradigm. Jimenez said, “They showed that myasma was wrong and then they said, this is not going to happen to us, this is superstition, this is something that we have to overcome.”
Pesky Little Drops
The rejection of aerosol transmission as a superstition carried a strong emotional charge that is still felt today. To explain disease transmission without direct contact, preference was given to the theory that pathogens would be carried through large droplets – the same type. Initially blamed for spreading Kovid.
In fact, COVID is not the first case where scientists have had to fight their way to enter aerosol transmission. Droplets were initially thought to be the cause of non-contact transmission of tuberculosis, measles and chickenpox, and only after irrefutable evidence would the scientific establishment accept the phenomenon of aerosol transmission.
“Something they told us at the WHO meeting, ‘Covid’ is [was] Not in the air like measles, if it was like measles we would have noticed. But in fact measles and chickenpox, which are both highly contagious airborne diseases, were described as droplet diseases until the 1980s,” Jimenez said.
Furthermore, he said, while much effort is made to prove each instance of aerosol transmission, not enough attention is paid to the fact that there is not enough evidence in droplet transmission. “Droplet transmission, which they told us and still tell us is the main mode [covid] transmission, it has not been demonstrated directly – not just for COVID, but for any disease in medical history,” Jimenez said.
Aerosol scientists say there is a physics misunderstanding in the theory of droplet transmission, but resistance is still strong among public health officials. “Over the past two years, there has been substantial discussion about the modes of transmission of COVID-19, particularly the way SARS-CoV-2 is transmitted through the air. […] It is a cross-cutting issue not only related to SARS-CoV-2, but also to other respiratory pathogens capable of causing a public health emergency of international concern,” by WHO spokeswoman Margaret Ann Harris with Quartz Read a statement shared. “WHO is now leading and coordinating an international technical consultation process with global experts to debate the issue and reach consensus.”
air sickness
Accepting airborne transmission has implications that go beyond infectious medicine, or rigid beliefs. If a disease spreads through direct contact or close proximity, the responsibility of preventing it may be placed on the individual. Protective equipment, distance, disinfect: These are all measures that people can take to prevent an outbreak. In this way, getting sick becomes a personal failure—people may not have washed their hands, or taken certain precautions.
But if the virus is in the air and someone becomes infected at a school or office, where they cannot control the quality of the air, the blame cannot be personal. Similarly, any face covering can prevent large droplets, but if certain types of masks (such as N95 respirators) are required, there is greater institutional involvement in ensuring that they are affordable, available, And some match the quality criteria. “The institutions—the CDC, the government, the WHO—remain in obscurity because it is so convenient,” Jimenez said.
Improvement: this article The amendment was made to clarify that only one person on the WHO team was rude andd shouted at Lidia Morawska during the April 2020 meeting.
(This story has not been edited by seemayo staff and is published from a rss feed)