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Prof. Jose-Luis Jimenez Profile picture
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Jan 20 • 19 tweets • 11 min read
1/ THE PENDULUM OF HISTORY OF AIRBORNE TRANSMISSION

As we revise our paper on this (papers.ssrn.com/sol3/papers.cf…), we've added draft diagram to summarize the history visually:

It'll be a few more days till we submit, so please reply with comments, clarifications, suggestions etc.
2/ If you haven't seen this, the short version:

- From Hippocrates and during most of human history, diseases were thought to transmit through the air (via a miasma)

3/ Miasma theory dominates till mid to late 1800s:

Cholera, Puerperal Fever, and Malaria (literally "Bad Air" in medieval Italian) were thought to transmit through the air. But demonstrated to transmit via water, hands, and mosquitos, respectively.

4/ A large paradigm shift takes place in late 1800s thanks to germ theory. It is a fluid time

Public Health Researcher Charles Chapin champions "contact infection", encounters much resistance. Especially bc of lingering belief on transmission through air

5/ Chapin proposes in 1910 book that ease of infection in close proximity is explained by sprayborne droplets, NOT airborne transmission

Proceeds to "discard" airborne trans. (w/o evidence): "A great relief to be freed from the specter of infected air"

6/ Chapin was very prominent, and infected air was scary and insidious. The medical and public health professions embrace his views enthusiastically. Chapin becomes @PublicHealth President in 1927, and #DropletDogma the law of the land.

play.google.com/store/books/de…
7/ By 1950, Alexander Langmuir, the first and longtime Director of the Epidemiology Branch of the @CDCgov (that referred to Chapin as "the greatest American Epidemiologist") states that it remains to be proven that any disease is airborne

8/ However, in 1962 Richard Riley, Cretyl Mills, and William Wells succeed in demonstrating that tuberculosis is airborne:

9/ However, TB is treated as unique exception. Intense dominance of #DropletDogma & resistance against airborne transmission continues

E.g. obvious case of airborne transmission of smallpox occurs. All investigators admit to being prejudiced against it

10/ Measles and chickenpox (now used as examples of prototypical airborne diseases) were considered DROPLET diseases from ~1910 till the 1980s.

Finally accepted as airborne due to obvious long range transmission:

11/ Still resistance to airborne transmission continues all the way to the COVID-19 pandemic.

At start of pandemic, @WHO convenes committee that decides how NEW disease is transmitted. They invite 6 handwashing experts, and 0 airborne / aerosol experts

12/ Finally the COVID pandemic brings intense focus on the errors of Chapin and #DropletDogma.

COVID-19 is predominantly airborne:

thelancet.com/article/S0140-…
acpjournals.org/doi/10.7326/M2…
13/ Not only that, but we already had evidence that most or all respiratory diseases have a component of airborne transmission:

14/ And in fact, we have more evidence for COVID-19 and the flu being airborne, than we have for the widely accepted airborne diseases! (measles, chickenpox, and tuberculosis)

science.org/doi/10.1126/sc…

15/ If this piqued your interest and you want to read something easier to understand than a Twitter thread, this recent short article from @crackedscience does a wonderful job of explaining the history (frankly better than I have explained it myself!):

16/ This 100+ tweet thread on the history (which I've linked a few times in the present thread) has a lot more details. It was written up into the preprint to which I've added the diagram shown in tweet #1 here: papers.ssrn.com/sol3/papers.cf…

17/ @DimitriNakassis and @AllanOlley in the comments pointed out that the date was labeled incorrectly for Hippocrates. Here is the new version with that fixed:
18/ And I forgot to link this outstanding @wired article, that summarizes some of the COVID-19 debate and the origins of the 5 micron error, with a lot of historical context. The research article it refers to is now published at: royalsocietypublishing.org/doi/full/10.10…

wired.com/story/the-teen…
@WIRED 19/ To clarify a confusing detail: the diagram just tries to represent the DOMINANT thinking. There were all kinds of theories, and every form of transmission was proposed many centuries ago.

We are trying to represent the DOMINANT thinking from a 10000 ft view

Caption of fig:

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More from @jljcolorado

Prof. Jose-Luis Jimenez Profile picture
Jan 21
1/ Sobre la transmisión de virus a muy gran distancia, como decía este señor que podía explicar que hubiera e.g. más casos en Cataluña vs. otras comunidades.

He dicho que es una tontería, y lo mantengo. Explico algunos detalles aquí: Image
2/ Esta es una pandemia DE INTERIORES. El virus se transmite por el aire, pero sobre todo hablando cerca o al compartir una habitación (como todos los casos de superpropagación), como en la imagen.

Muchos más detalles aquí: Image
3/ Hay bastantes casos documentados de transmisión por el aire a más distancia en interiores (sin estar en la misma habitación al mismo tiempo), por ejemplo en hoteles de cuarentena en Nueva Zelanda, Hong Kong etc. Como este caso por flujos bajo puertas:

Read 13 tweets
Prof. Jose-Luis Jimenez Profile picture
Jan 19
@CIBSE_NatVent I have run the case on our estimator at docs.google.com/spreadsheets/d…

- Note ventilation rate is relatively high, most schools don't meet it

- Leads to CO2 = 1720 ppm, while some of your colleagues in the UK say it is fine if it is < 5000 ppm

Vent rate for 5000 ppm is 1 l/s/p, NOT 5
@CIBSE_NatVent With 5 l/s/p, adding the RELATIVELY SMALL cleaner with CADR = 100 l/s (ACH = 2.4 on cell B31) the risk goes down 30%

With an EXPONENTIALLY growing disease, that's a lot, because it is 30% off EACH GENERATION. I.e. compound interest
@CIBSE_NatVent With the "barely acceptable according to some UK experts" case with 4999 ppm CO2 (~1 l/s/p), then adding that smaller air cleaner reduces the risk 45%.

I would definitely prefer to have my son in a class with the cleaner than without the cleaner
Read 5 tweets
Prof. Jose-Luis Jimenez Profile picture
Jan 17
1/ El exasesor de Obama predice qué pasará en España en primavera

"Rafael Bengoa, experto en gestión sanitaria y exconsejero de Sanidad del País Vasco, aconseja reforzar el sistema de salud de España: “Su situación es la peor de su historia”"

as.com/diarioas/2022/…
2/ Entrevista interesante

"Ómicron no es el fin, COVID-19 vino para quedarse y lo más sensato es aumentar la capacidad del sistema de salud y crear condiciones favorables en las aulas para evitar contagios entre niños. “La atención primaria es nuestro banquillo. Hay q fichar”"
3/ "La situación va a ser de agobio total en enero y principios de febrero por el decalaje. Esto ha creado una demanda sobre el sistema de salud, probablemente la peor de su historia durante este mes. Con menos mortalidad, pero con una demanda absolutamente brutal."
Read 11 tweets
Prof. Jose-Luis Jimenez Profile picture
Jan 16
1/ El artículo CORTO MEJOR y MÁS CLARO que he leído sobre la transmisión por el aire de COVID-19:

- Por qué la historia llevo a la OMS a negarla
- Cómo protegernos

Traducción automática del artículo de @crackedscience

www-mcgill-ca.translate.goog/oss/article/co…
2/ "El 28-Mar-2020, al comienzo de la pandemia, la OMS @WHO tuiteó : “HECHO: #COVID19 NO se transmite por el aire”.

"Para los médicos y científicos biomédicos (incluyéndome a mí), esto tenía sentido. Se sabía que pocas enfermedades se transmitían por el aire."
3/ "Pero para los científicos de aerosoles, esto era a la vez desconcertante y exasperante."

"En siguientes 2 años, OMS y otras organiz. q inicialmente habían negado q el nuevo coronavirus pudiera permanecer en el aire y moverse como el humo cambiaron silenciosamente su postura"
Read 12 tweets
Prof. Jose-Luis Jimenez Profile picture
Jan 16
1/ Must read from Dr. Raina MacIntyre:

Key quotes:

"As for denial of the risk in children, the majority of vaccine-preventable diseases that we vaccinate children against are mild in most children. Only a small percentage suffer serious complications"

thesaturdaypaper.com.au/opinion/topic/…
2/ From @Globalbiosec:

"The denial of the airborne transmission was started by experts on @WHO IPC committee & allowed all countries to take the easy way out. If handwashing is all you need, onus can be shifted to “personal responsibility”...
3/ "... if ventilation needs to be fixed, that shifts responsibility to governments and private organisations."

"Denial of Omicron being serious suits exhausted community who wish life could go back to 2019. Omicron may be 1/2 as deadly as Delta, but D was 2x as deadly as 2020"
Read 11 tweets
Prof. Jose-Luis Jimenez Profile picture
Jan 15
The BEST and CLEAREST short article I have read about AIRBORNE transmission of COVID: why history led to it's denial, and what to do about it

By @crackedscience

HT @KimABowie & @JANEMCARTHUR11
mcgill.ca/oss/article/co…
If you want more details on the history, the short version in that article summarizes this preprint of ours:

papers.ssrn.com/sol3/papers.cf…

In review, will hopefully pass peer-review soon
And a summary of the history and the early pandemic in this excellent article by @MeganMolteni in @WIRED, that reads like a detective story:

wired.com/story/the-teen…
Read 4 tweets

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