Thread by @BarryHunt008

🧵 "Cough into your elbow" has no peer-reviewed origin

Researchers traced it to a 2006 hospital video

And a 1994 quote from a pediatrician who said she learned it from daycare

Neither CDC nor WHO can tell you who invented it

It's just folklore that gained a following

Here's what the evidence actually says 👇

📄 Zayas et al. 2013: pmc.ncbi.nlm.nih.gov/articles/PMC38…

Both WHO (2006) & CDC (2007) admitted that cough etiquette recommendations were made "on the basis of plausible effectiveness rather than controlled studies"

That was 20 years ago

The evidence base has barely moved since

This is IPC dogma, not evidence-based practice

A 2020 study in Physics of Fluids used Schlieren imaging to visualize cough plumes under 9 different covering conditions

Finding: a BARE elbow cannot form a seal against the face

Aerosol leaks in multiple directions

📄 Simha & Rao 2020: pubs.aip.org/aip/pof/articl…

A 2025 University of Utah study compared cough maneuvers directly using slow-motion video

Elbow - 59.6% reduction

Surgical mask - 93.2% reduction

INTO THE SHIRT - 95.4% reduction

The shirt beat the elbow by 36 points

📄 Steimle et al. 2025: pmc.ncbi.nlm.nih.gov/articles/PMC12…

A 2013 University of Alberta laser-diffraction study measured droplet size during cough etiquette maneuvers

97% of cough droplets <1 micron

Particles escaped regardless of maneuver - elbow, tissue, hands, surgical mask

📄 Zayas et al. 2013: pmc.ncbi.nlm.nih.gov/articles/PMC38…

Ranking:

1. N95 - 94-99% aerosol reduction

2. Into the SHIRT - 95.4%

3. Surgical mask - 93-94%

4. Multi-layer fabric / towel - ~77%

5. Tissue - large droplets

6. Cupped hands - some containment

7. Bare elbow - leaks in multiple directions

📄 Lindsley et al. 2021: tandfonline.com/doi/full/10.10…

Tip: Try to PREVENT sneezes

1. Press firmly below your nose (philtrum) when you feel a sneeze coming (stimulates trigeminal nerve, can abort the reflex)

2. Press your tongue hard against your hard palate simultaneously

Competing touch signals interrupt irritant cascade upstream of the motor program (gate control theory)

📄 Mechanism: upstate.edu/whatsup/2017/0…

❌ DANGEROUS: Clamping nose & mouth shut during an active sneeze

Pressure has nowhere to go

Risk of pharyngeal rupture, eardrum rupture, even aneurysm

✅ SAFE: Interrupting the sneeze BEFORE it fires - tongue to palate + philtrum pressure aborts the afferent signal BEFORE motor execution

📄 BMJ case report on suppression dangers: bmj.com/content/360/bm…

Is it safe to suppress a sneeze as long as you don't block the exits?

No

Yes

Maybe

Depends who you ask

Depends on your training

Could be a teachable skill

If you're a trained scuba or freediver who uses Frenzel equalization, you have voluntary control over:

· Glottis closure (decoupling lung from upper airway)
· Soft palate position
· Nasopharyngeal pressure management

IN THEORY, you can safely suppress a sneeze

I practice this regularly (if / when I react too slowly to prevent a sneeze)

No study has tested this

Someone should

📄 Frenzel mechanism: en.wikipedia.org/wiki/Frenzel_m…

Any condition causing REPEATED coughing or sneezing (cold, flu, COVID, allergies) should be a trigger to wear a respirator in shared spaces

Before the cough happens

This should be standard in healthcare

And become a cultural norm everywhere

"I might be coughing or sneezing but I'm not sick - why would I need a respirator?"

6% of apparently healthy people are actively shedding respiratory virus at any given time

57-93% of positive respiratory virus samples come from asymptomatic individuals

Human bacterial pathogens (S. aureus, H. influenzae, MRSA) have been detected in exhaled breath of healthy carriers

Your respiratory microbiome is real

Whether it's pathogenic to the person next to you depends on THEIR immune status, not yours

📄 Asymptomatic shedding: journals.asm.org/doi/10.1128/ms…

📄 Exhaled breath pathogens: pmc.ncbi.nlm.nih.gov/articles/PMC70…

"I'm not sick, it's just allergies"

Wear a respirator

1. You will inhale less pollen → fewer sneezes, less misery (36% reduction in moderate-severe nasal symptoms in mask-wearers with pollen allergy)

2. Your repeated high-velocity sneezes are dispersing your respiratory microbiome to everyone around you

Wearing a respirator during allergy season protects YOU primarily

The protection of others is a co-benefit

📄 Pollen + mask evidence: pmc.ncbi.nlm.nih.gov/articles/PMC84…

So here's what the evidence actually supports:

1. PREVENT the sneeze

Philtrum pressure + tongue to hard palate the moment you feel it coming

Takes practice

Teachable to most people

Works ~70-80% of the time once learned.

Divers: use what you already know.

2. COVER for what gets through

Shirt > tissue > cupped hands

Never bare elbow alone

Two-handed elbow (pressing arm firmly to face) is mechanistically better but still inferior to shirt

3. REPEATED symptoms = wear a respirator

Before the cough or sneeze, not instead of covering

Protects you from your own triggers

Protects others from your unknowns

None of the following have ever been studied:

Does one-handed bare elbow form a seal on anyone?

What is the success rate of pre-sneeze suppression in a taught population?

Do Frenzel-trained individuals safely dampen sneeze aerosol output?

What does tissue achieve vs. elbow in a head-to-head standardized study?

Does the shirt maneuver hold up with n>5?

We have had 20 years and essentially 5 small studies

For a behaviour performed billions of times per day

If you work in IPC, respiratory medicine, or aerobiology: these are your research questions.

The elbow maneuver spread globally not because of evidence but because a hospital in Maine made a funny video in 2006

We can do better

Prevent > Cover > Protect

And for repeated symptoms: wear a respirator

Share if your IPC training never included any of this