2/ Remember, the evidence is overwhelming that airborne transmission (1 to 1 in close proximity, and 1 to many in shared room air = superspreading) is the dominant mode of transmission.https://twitter.com/jljcolorado/status/1383566908797059078 …
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3/ And probably we are being charitable by saying only "dominant." Can't find any real evidence that airborne is not 99%. Airborne can explain all the epidemiological patterns, while large droplets and fomites can't, and they are pathetically lacking ev.https://twitter.com/jljcolorado/status/1390497149574651906 …
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4/
@zeynep published an outstanding article yesterday in the@nytimes where she explains the context, the implications, and some of the history. I wanted to give some more historical detail, without the word limits that she faced in@nytimes.https://www.nytimes.com/2021/05/07/opinion/coronavirus-airborne-transmission.html …Show this thread -
5/ Why does this matter? bc we still face resistance. We have seen how
@WHO and others do the changes too quietly, and they don't communicate how the mitigations need to change. And in many countries they report that mssg doesn't arrive, still focusing on disinfection + plexiglasShow this thread -
6/ We have written an article on history. Started by trying to figure out where 5 micron error for droplet / aerosol boundary came from, since physics tells us it is ~100 um. E.g. see this video of 50 micron particles, ain't falling to the ground quickly:https://twitter.com/MicroLevitator/status/1283556047471378432 …
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8/ Our preprint on the history can be read here. Written by
@katierandall,@EThomasEwing,@linseymarr, Lydia Bourouiba and yours truly. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3829873 …Show this thread -
9/ We need to go back to the origins of theories about the transmission of diseases. Hippocrates (https://en.wikipedia.org/wiki/Hippocrates …) in ancient Greece proposed that diseases were transmitted through the air. [I think doctors still do the Hippocratic Oath: https://en.wikipedia.org/wiki/Hippocratic_Oath …]
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The Hippocratic text "On the Nature of Man" reads: "Whenever many men are attacked by one disease at the same time, the cause should be assigned to that which is most common, and which we all use most. This it is which we breathe in."https://www.loebclassics.com/view/hippocrates_cos-nature_man/1931/pb_LCL150.25.xml …
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11/ Throughout much of human history, belief persisted that diseases were transported through the air. Coming from putrid matter, traveling long distances (e.g. a person infected by the flu in Boston could infect someone in UK) This was miasma theory:https://en.wikipedia.org/wiki/Miasma_theory …
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12/ The idea of person-to-person transmission, which now seems obvious (e.g. we get COVID-19, the flu, or tuberculosis from another person) wasn't seriously considered till Italian physician Girolamo Fracastoro proposed it in 1546:https://en.wikipedia.org/wiki/Girolamo_Fracastoro …
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13/ The debate ensued for centuries between the miasmatists and the contagionists. https://oyc.yale.edu/history/hist-234/lecture-13 …
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14/ A middle ground was devised, "Contingent Contagionism"https://en.wikipedia.org/wiki/Contingent_contagionism …
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15/ CC was "a qualified way of rejecting application of term "contagious disease" for a particular infection. E.g. it could be stated that cholera, or typhus, was not contagious in a "healthy atmosphere", but might be contagious in an "impure atmosphere"https://en.wikipedia.org/wiki/Contingent_contagionism …
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16/ Eerie how that applies to COVID-19. Highly contagious under some low ventilation conditions, much less so under well ventilated or outdoor conditions. E.g. our preprint, where we reproduce indoor superspreading quantitatively with an airborne model:https://twitter.com/jljcolorado/status/1388948704384725000 …
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17/ Florence Nightingale was a contingent contagionist. During the Crimean war in the 1850s, she greatly reduced infection rates with social distance & ventilation.https://en.wikipedia.org/wiki/Florence_Nightingale …
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18/ In 1854, there is a cholera epidemic in London. The public health established believed it to be caused by a miasma (bad air). John Snow (https://en.wikipedia.org/wiki/John_Snow ) shows that it is transmitted through water!
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20/
@DFisman explained in this brilliant thread why the establishment was so keen on rejecting water as the source of cholera: they had a lot to lose, including their prestige by admitting they had been so wrong. Snow was outsider & could afford fighthttps://twitter.com/DFisman/status/1297676282755506177 …Show this thread -
21/ Ignaz Semmelweis was another pioneer of disease transmission (https://en.wikipedia.org/wiki/Ignaz_Semmelweis …). In 1847, he figured out that handwashing greatly reduced deaths by childbed fever in a maternity clinic:
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22/ These are some of Semmelweis' data (https://en.wikipedia.org/wiki/Ignaz_Semmelweis …): I'd call that pretty convincing and certainly worth a serious look.pic.twitter.com/gRKOccyKhw
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23/ But Semmelweis's was largely ignored, rejected, or ridiculed. He was dismissed from hospital for political reasons and harassed by medical community in Vienna, being eventually forced to move to Budapest. After some years broke down, was interned & beated, died of infection
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24/ In the 2nd half of the 19th Century, Pasteur and Koch demonstrate the germ theory of disease:https://en.wikipedia.org/wiki/Germ_theory_of_disease …
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25/ Germ theory is not accepted overnight: "By the end 1880s, miasma theory was struggling to compete. Viruses were initially discovered in the 1890s. Eventually, a "golden era" ensued, with identification of the actual organisms that cause many diseases.https://en.wikipedia.org/wiki/Germ_theory_of_disease …
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26/ In the 1990s Carl Flugge in Germany sets out to disprove the then dominant theory, that tuberculosis is transmitted when the dry sputum of the sick goes back into the air.https://en.wikipedia.org/wiki/Carl_Fl%C3%BCgge …
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27/ Flugge thought that it was not the dried secretions from the sick that went back to infect, but rather the fresh secretions were leading to infection before reaching the ground. We explain this in paper (Lydia B. read the original papers in German) https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3829873 …
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28/ Although it has been attributed to him (e.g. erroneously in Wikipedia: https://en.wikipedia.org/wiki/Carl_Fl%C3%BCgge …), he didn't push "Flugge's droplets" that fell to ground. They waited 5 hours for droplets AND aerosols to settle from the air!!
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29/ In 1905 a speaker at the pulpit of the expansive UK House of Commons gargled with a broth culture of B. prodigiosus before reciting Shakespeare passages in a loud voice to the empty room...
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30/ ... although growth colonies were more numerous in plates near the speaker, cultures were apparent on plates over 21 m away. https://play.google.com/books/reader?id=VcBDAQAAMAAJ&hl=en&pg=GBS.RA11-PA66 …
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31/ So we get to the critical point in the history, the work of prominent American epidemiologist Charles V. Chapin. He was very successful, in 1927 the President of American Public Health Association.https://en.wikipedia.org/wiki/Charles_V._Chapin …
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