コロナパンデミックで進んだ空気感染(=airborne transmission)の概念｜空気感染が否定されてきた歴史(2022.8.25作成) #エアロゾル #新型コロナウイルス #水疱瘡 #麻疹

Prof. Jose-Luis Jimenez @jljcolorado

65/ As we have explained in another recent paper, Chapin conflates an empirical fact ("distance reduces transmission") with a mechanism: GRAVITY, which makes the droplets fall close to the infected person. doi.org/10.1111/ina.13…

Prof. Jose-Luis Jimenez @jljcolorado

66/ Problem: the more correct explanation (of why distance reduces trans.) is NOT gravity but DILUTION: Like exhaled smoke, you breathe less exhaled air farther from someone. And error in PHYSICS made by MEDICAL professionals who do not study physics! onlinelibrary.wiley.com/doi/10.1111/in… pic.twitter.com/giZ2ZHJnxZ

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Prof. Jose-Luis Jimenez @jljcolorado

67/ Despite the lack of evidence, Chapin was too successful. He was much better positioned than Snow or Semmelweis as the long-serving Health Officer of Providence and w/ success of reducing contact transmission iin a new hospital. In 1927, he became President of @PublicHealth

Prof. Jose-Luis Jimenez @jljcolorado

68/ Chapin was described in 1967 as “the greatest American epidemiologist” by A. Langmuir, 1st & long-time director (1949–1969) of epidemiology branch of @CDCgov As late as the 1980s, Chapin's views were dominant there. doi.org/10.1093/aje/14… en.wikipedia.org/wiki/Alexander… pic.twitter.com/kn2y47Wd9v

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Prof. Jose-Luis Jimenez @jljcolorado

69/ CRITICALLY, Chapin's unproven hypothesis was accepted as true: Ease of infection in close proximity is accepted proof of transmission from sprayed droplets This KEY ERROR conditioned the evolution of this field over the next century, and into the COVID-19 pandemic

Prof. Jose-Luis Jimenez @jljcolorado

69/ The 1918 flu led to lots of work and discussion in this area, but did not blunt the ascendance of of Chapin's theory: onlinelibrary.wiley.com/doi/10.1111/in… pic.twitter.com/ABJq8XFkbA

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Prof. Jose-Luis Jimenez @jljcolorado

70/ In the 1930s, Harvard engineering professor William Wells and physician Mildred Wells, his wife, started applying more contemporary experimental methods to the investigation of airborne transmission. en.wikipedia.org/wiki/William_F… pic.twitter.com/DKg045Mohd

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Prof. Jose-Luis Jimenez @jljcolorado

71/ But Chapin had successfully shifted the paradigm and his theory was now viewed as scientific progress. The Wellses were accused of a retrograde approach to science, which sought to bring back the miasma theory. jamanetwork.com/journals/jama/… pic.twitter.com/I18K8myfH8

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Prof. Jose-Luis Jimenez @jljcolorado

72/ Wells was 1st to rigorously study size of sprayborne droplets vs. airborne aerosols Conceptualized dichotomy of sprayborne droplets (≳100 μm), reach the ground before drying Vs. aerosols (≲100 μm), dry before they reach ground ( “droplet nuclei”) academic.oup.com/aje/article-ab… pic.twitter.com/A8rmlTKXrt

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Prof. Jose-Luis Jimenez @jljcolorado

73/ Wells understood connection w/ meteorology where this is common knowledge, stating: “A raindrop 2 mm in diameter can fall miles without completely evaporating under conditions which would cause a 0.2 mm droplet to evaporate before it had fallen from the height of a man.” pic.twitter.com/KjAfXwTpqo

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Prof. Jose-Luis Jimenez @jljcolorado

74/ Shockingly, Public Health and Infectious Diseases have published for decades that large droplets are those heavier than 5 microns (!!). Including in the latest @WHO Scientific Brief on COVID Transmission that addresses this issue: pic.twitter.com/zfMD5lsKKX

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Prof. Jose-Luis Jimenez @jljcolorado

@WHO 75/ We pointed out this glaring error many times. I.e. see that even at 50 microns, they don't fall quickly: Not too important per se, but makes glaringly obvious the ignorance of physics by those in charge at @WHO and its IPC committee. twitter.com/MicroLevitator…

Ryan Davis @MicroLevitator

Much discussion lately in aerosol/disease transmission communities about the “5 micron cutoff” where droplets supposedly fall to ground w/in 1-2 m. @jljcolorado and @linseymarr has suggested ~50 microns. Here’s some video evidence for that. 50 micron droplets wafting in lab... pic.twitter.com/5SrE7GeKDF

2020-07-16 09:16:23

Prof. Jose-Luis Jimenez @jljcolorado

76/ We investigated the history of the 5 micron / 2 meters error in a previous paper led by @linseymarr and the extraordinary @katierandall, with support from @EThomasEwing, Lydia Bourouiba of @MIT and yours truly: royalsocietypublishing.org/doi/10.1098/rs…

Prof. Jose-Luis Jimenez @jljcolorado

77/ I am getting slightly out of order. I'll explain the reason for the "5 micron particles fall within the meters of the person" enormous error later in the thread, once I have explained the background. So we were talking about the work of William Wells on airborne infection.

Prof. Jose-Luis Jimenez @jljcolorado

78/ The Wellses suspected that tuberculosis and measles were airborne, but BOTH were already believed to be droplet diseases, and they encountered intense resistance from the epidemiological community.

Prof. Jose-Luis Jimenez @jljcolorado

79/ Measles was thought to be a droplet/fomite disease. At the time of Wells... and as late as 1985, because of: - ease of transmission in close proximity (= sprayborne droplets per Chapin) - cases of lack of infection w/ shared air pediatrics.aappublications.org/cgi/pmidlookup… pic.twitter.com/KTDSxXIgw1

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Prof. Jose-Luis Jimenez @jljcolorado

80/ Wells thought that measles was airborne (and now we know he was correct, though he died 2 decades before this was accepted) Wells has some initial success showing that UV lights installed in the ceiling of classrooms greatly reduced measles infection ajph.aphapublications.org/doi/10.2105/AJ… pic.twitter.com/dO7aMZs6DQ

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Prof. Jose-Luis Jimenez @jljcolorado

81/ However, subsequent attempts to replicate these findings produced mixed results. In retrospect, in schools where UV prevented measles transmission, children were together indoors only in the school, not elsewhere. In other schools, children shared other spaces (e.g. buses)

Prof. Jose-Luis Jimenez @jljcolorado

82/ Wells established the scientific basis of airborne infection But he was working in a period of intense hostility in public health and inf. diseases towards airborne tr., ushered by the success of the 1910 paradigm shift of Chapin after 2 millenia of belief in miasmas pic.twitter.com/kEUnHsYDn4

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Prof. Jose-Luis Jimenez @jljcolorado

83/ General skepticism against airborne tr. is illustrated by 1951 quote of Langmuir (first and longtime director of epidemiology @CDCgov) : “It remains to be proved that airborne infection is an important mode of spread of naturally occurring disease" jstor.org/stable/4587679

Prof. Jose-Luis Jimenez @jljcolorado

84/ Langmuir worked preventing disease trans. among US military in WW II Substantial resources were dedicated to the effort, generating knowledge “which would have taken decades to accumulate under peacetime conditions” & established leaders for decades doi.org/10.1093/aje/14…

Prof. Jose-Luis Jimenez @jljcolorado

85/ Langmuir et al. studied airborne transmission, but MISINTERPRETED the results of their own studies: Distance reduced transmission, therefore it was droplets. Ignoring that distance reduces airborne transmission by dilution. doi.org/10.1093/aje/14… doi.org/10.1111/ina.13… pic.twitter.com/YGU1HF9Yec

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Prof. Jose-Luis Jimenez @jljcolorado

86/ However, Langmuir's work renewed interest in airborne infection, as he concluded that WEAPONS of airborne disease could be created, which became a topic of intense interest during the cold war. jstor.org/stable/4587679

Prof. Jose-Luis Jimenez @jljcolorado

87/ Despite stubborn resistance to the idea that airborne transmission had relevance for natural diseases, Wells, Robert Riley [pic] & Cretyl Mills succeeded in demonstrating airborne transmission of tuberculosis (TB) in 1962 through extensive efforts doi.org/10.1164/arrd.1… pic.twitter.com/oD3VUGCloz

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Prof. Jose-Luis Jimenez @jljcolorado

88/ They routed air from TB hospital ward to 150 guinea pigs (GP) for 2 yrs. ~3 GP / month were infected No GP infected in control group where the only difference was that the air was irradiated with germicidal ultraviolet light, killing the TB bacterium doi.org/10.1164/ajrccm… pic.twitter.com/aVje6Jfs4O

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