Jennifer K McDonald Profile picture
MD, Physiatrist, pro-ultrasound, anti-pain, not just a needle jockey, views are my own
Peter English #FBPE Profile picture Tim Delaney ⭐⭐ Profile picture Aviva Gabriel Profile picture Papa De Razón Profile picture 4 added to My Authors
Mar 25 4 tweets 4 min read
What to do when covid isolating?#MaskRAT 😷 🐀

This illustrates:
1) importance of masking for source control
2) overdispersed nature of transmission

Top mask worn for ~45 min by person with strong RAT nasal swab, mask tested within 5 min, inside of mask was dry.

1/4 In this N of 2 experiment, the strength of RAT result on standard throat/nasal swab correlated with #MaskRAT result.

The bottom person (me) had multiple negative #MaskRATs and barely detectable nasal/throat RAT for 1 day (day 5)

Feb 13 12 tweets 6 min read
#BetterMasks for kids < 5 yo

☑️ Filtration
☑️ Fit
☑️ Function

A short thread 🧵

Optimize filtration material:

☑️Surgical masks are good
Look for ASTM-rated

✅Respirators are best
Look for standardized filters:
Canadian - 95PFE
South Korean- KF94
Chinese - KN95

Jan 10 12 tweets 4 min read
#BetterMasks #FitFiltrationFunction

@masknerd’s google docs excel sheet tabulating all his mask testing results is a goldmine of information!

I highlighted some of his data in the pictured table to further explore the validity of the “well-fitting medical mask” narrative

1/ A few ASTM level 3 surgical masks were tested. Worn without modification, they had a filtration efficiency of 35-78% (via particle counter).

(Side note- don’t twist the ear loops- it makes the fit worse)

Is > 20% leak well-fitting? Not in my books.

Jan 8 8 tweets 4 min read
Looking for a #BetterMask but:
✖️N95s are harder to find than TP in 2020
✖️you can’t afford N95s and your government isn’t making them accessible
✖️your workplace mandates medical masks and doesn’t allow N95s
✖️your school gives students medical masks

This 🧵‘s for you

Ensure your medical mask is ASTM graded and is at least a grade 2 mask, preferably grade 3 (will ensure better filtration performance of the mask material)

Important to note, ASTM 3 does not imply or guarantee respirator-quality filtration performance.

Dec 19, 2021 15 tweets 5 min read
To the experts insisting “N95s are useless if not fit-tested”

Have you ever tried to fit test a “well-fit surgical mask” or “3 layered well-fit cloth mask”?

TLDR they are inferior.

A brief case series and 🧵

1/15 There are two type of fit tests, 1) quantitative fit testing - a portacount machine measures the concentration of aerosol outside the mask versus inside the mask and 2) qualitative fit testing - a potent bitter or sweet aerosolized solution is inhaled under a hood

Oct 17, 2021 10 tweets 5 min read
We've summarized the literature supporting airborne transmission of COVID-19 & several other respiratory pathogens. Guess what? #COVIDisAirborne #FluisAirborne #SARSisAirborne #MERSisAirborne

Live version of table & refs:

@jmcrookston @jljcolorado
1/ Original version of table here:

Jul 28, 2021 7 tweets 2 min read
TL;DR The Tome of Nuance

IMHO this review muddies the messages and flip flops on key mitigation strategies When the science and our understanding evolves, it’s important to communicate this clearly and concisely to the public rather than fall back on nuance and shades of gray. Even when this means admitting that previous messaging was incorrect.
May 1, 2021 4 tweets 3 min read
I wear an N95 respirator to protect myself, my patients, my colleagues and my family. Blocking inhalation and exhalation of potentially infectious particles just makes sense during a respiratory pandemic. #PerfectFit on the PortaCount #SayNoToSafetyStewardship #FreshAirWeCare Image Because a fit factor of 5 (20% leak) - when quietly breathing through a surgical mask - isn’t respiratory protection.
Apr 15, 2021 4 tweets 1 min read
“During the great COVID pandemic of 2020, you may be shocked to learn that many international ID experts believed that respiratory viruses spread primarily through fomites and eyes, rather than the more obvious route - inhalation...” “As the pandemic swept across the globe, and cases grew, so did the evidence supporting aerosol transmission. The increased risk in shared indoor air and poorly ventilated spaces and decreased risk outdoors was plain for all to see.”
Mar 25, 2021 4 tweets 1 min read
Review of available evidence supporting fomites transmission

TLDR: there is no evidence Current IPAC policies are heavily weighted towards preventing droplet/fomites spread and active nosocomial outbreaks are blamed on HCWs for not tying gowns correctly, other donning/doffing errors, not wearing proper face shield, etc
Mar 22, 2021 18 tweets 8 min read
It's widely accepted that #MeaslesIsAirborne

I summarized the evidence for airborne spread of Measles vs. COVID-19 in a table

The results were quite shocking to me ...

How is it that we are still discussing whether or not #COVIDisAirborne??

1/ The disease on the left is managed with airborne precautions, including respiratory protection (N95/respirator) and ventilation optimization