Thread by @rkhamsi

THREAD🧵--> For weeks, I've been tracking the scientific debate about whether we need masks to prevent transmission of the virus causing #COVID19 and whether it is #airborne. If you're confused, you are not alone. Stick with me here. Let's clear the air. 1/15

On Saturday, the World Health Organization used CAPS to say, "FACT: #COVID19 is NOT airborne." Here is the tweet. But keep reading this thread, because the wording is tricky.

https://twitter.com/WHO/status/1243972193169616898

As I wrote about 2 weeks ago, essentially, the word 'airborne' means something traveling in the air. But public health officials rely on a cutoff that any tiny bit of mucus larger than 5 microns in diameter that you cough out is called a 'droplet' 3/15 wired.com/story/they-say…

Why that cutoff? The idea of separating large 'droplets' from smaller 'aerosols' dates back to the 1930s (!!!). William Wells and his team proposed that pathogens could spread by air. Later, they housed guinea pigs above tuberculosis patients in a hospital to prove this. 4/15

The guinea pigs got sick with tuberculosis. Yet there was pushback against the airborne theory of transmission. Some aerobiologists say this was a reaction to the widely debunked 'miasma theory' in which poisonous vapors were said to be the culprit in the spread of illness 5/15

Fast forward to March 14, 1977, when a plane was grounded for 3 hours without ventilation. There was an ill person on board with flu symptoms. Within days 72% of the 54 people aboard got sick. Yet there's still debate about how 'airborne' flu is. 6/15 ncbi.nlm.nih.gov/pubmed/463858

At the time I wrote my story two weeks ago, there were already concerning reports. In a @JAMA_current study of hospital isolation rooms in Singapore, air vent blades in one patient’s room did test positive for #SARSCoV2 (the #COVID19 virus): jamanetwork.com/journals/jama/… 7/15

Another study, from Wuhan, found that the levels of #SARSCoV2 in most #COVID19 patients' rooms were undetectable or low, but it did find the presence of the virus in aerosol form. It is still not peer-reviewed, so proceed with caution. 8/15 🛑biorxiv.org/content/10.110…

More recently, Nebraska researchers including @Prof_Lowe detected #SARSCoV2 in air samples collected from patients rooms. Finding traces of virus isn't the same as proving they are infectious. Could just be genetic skeletons. But it is worth noting. 9/15 medrxiv.org/content/10.110…

OK, so we've just listed some recent studies. But what might have caught your attention is this intriguing graph markup by @jperla. Look at the 'mask countries' vs the 'no mask' countries. 10/15:

A lot of folks have also heard about the case of a choir, reported here by @RichReadReports. Sixty people showed up for rehearsal, 45 have been diagnosed with #COVID19 or have symptoms, at least 3 have been hospitalized, and 2 are dead. 11/15 latimes.com/world-nation/s…

This is all concerning. And as @zeynep presciently wrote a couple weeks ago: "The top-down conversation around masks has become a case study in how not to communicate with the public." 12/15 nytimes.com/2020/03/17/opi…

Fast-forward to this week. @KnvulS's article aptly captures the changing tide: "More Americans Should Probably Wear Masks for Protection" -- the tone is starting to shift. 13/15 nytimes.com/2020/03/27/hea…

Public health experts distinguish between 'face masks' such as surgical masks that are loosely fitting and 'respirators' like N95s. Why are they called N95s? Because they filter out 95% of particles smaller than 0.3 microns if properly fitted. Here's the FDA's explanation 14/15

Wanna know what makes mask manufacturing so special? MELT-BLOWN FABRIC. Unfortunately, not something that you find at your local craft store. Here's a story by @EmilyZFeng and @Amy_23_Cheng @ 15/n npr.org/sections/goats…

If you'd like to get your blood boiling, then read this story about how on Feb 5, HHS Secretary Azar requested $2 billion to buy supplies like respirator masks for the national stockpile. That request was cut 75% by the Trump administration: 16/n washingtonpost.com/national/healt…

What to do? @jeremyphoward "Yes, there is a shortage of manufactured masks, and these should go to hospital workers. But anyone can make a mask at home by cutting up a cotton T-shirt, tying it back together and then washing it at the end of the day." 17/n washingtonpost.com/outlook/2020/0…

MIT prof Lydia Bourouiba says:

"Wearing of appropriate personal protection equipment is vitally important for health care workers caring for patients who may be infected, EVEN IF THEY ARE FARTHER THAN 6 FEET AWAY from a patient."

(CAPS MINE) 18/n jamanetwork.com/journals/jama/…

Would you rather see an explainer on #airborne transmission on @YouTube? Here is @MIT prof Lydia Bourouiba's @TEDMED talk on how diseases and epidemics move through a breath of air. 19/n tedmed.com/talks/show?id=…

And here's Prof. Bourouiba on the @EPIDEMICpodcast (and me) talking about this 'false dichotomy' between droplets and fine aerosols. podcasts.apple.com/us/podcast/bon…
And here's me talking more about this on the recent #Resetpod 20/n podcasts.apple.com/us/podcast/air…

Ughhh. I am really bad at making a #Thread. It's taken me 2 hours and I forgot the most important thing:
1. Health officials say #COVID19 not airborne because they say it is only spread by large 'droplets'
2. But large droplets can travel farther under certain conditions 21/n

For example, aerobiologists point out that wind can carry large droplets far (think about the sea spray off of waves at the ocean on a windy day). They also say cough/sneeze droplets can sometimes go beyond 6 feet when taking into account the force of the 'cloud' you exhale 22/n

Last tweet on this. @linseymarr has been 100% amazing at #scicomm on this subject. Follow her. Also, the GIF in the initial tweet is from Julian Tang in the journal @PLOSONE.

QED: We all need masks, but healthcare workers REALLY need proper masks.

23/n

But wait... there's more!
@ferrisjabr has this incredible new story in @WIRED on why widespread mask wearing is an essential public health measure. He writes, "The collective evidence makes a strong case for universal mask wearing during a pandemic."

24/n wired.com/story/its-time…

CORRECTION: # 14 out of 15 in this thread should have read: "Because they filter out 95% of particles LARGER than 0.3 microns if properly fitted."

25/n

One more chilling study for this #Thread. Middle East Respiratory Syndrome is a cousin of #COVID19. In 2015, a 35-year old man exposed 1,600 people in an ER to MERS, infecting 82 folks: 33 patients, 8 staff + 41 visitors.

Here's the press release:

26/n

sciencedaily.com/releases/2016/…

I’m mortified that I neglected to give a shout out to the awesome aerobiologist @Don_Milton in this thread. He rules! When asked about why the WHO resists the idea of airborne #COVID19 he says: “I think they are talking out of their hats.” 27/n npr.org/2020/03/28/823…