sharon sanders
Editor-in-Chief & President
My bolding...
https://www.hsph.harvard.edu/joseph-allen/
Joseph Allen
@j_g_allen
I see a lot of people - on both "sides" - making simple mistakes about masks. I've studied PPE, taught PPE, and overseen PPE programs, including teams implementing fit testing in hospitals, long before covid. A thread
8:03 AM · Dec 29, 2021·Twitter Web App
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Tweet your reply
Reply
Joseph Allen
@j_g_allen
·
1h
Replying to
@j_g_allen
1. Masks work It's basic physics.
nytimes.com
Masks Work. Really. We’ll Show You How (Published 2020)
A visual journey through the microscopic world of the coronavirus shows how masks provide an important defense against transmission.
3
10
77
Joseph Allen
@j_g_allen
·
1h
I made one of the earliest calls for universal masking, for that reason. April 2, 2020
washingtonpost.com
Opinion | You need to wear a mask. Here’s how.
Everyone should be covering their faces. Here's how to do it correctly.
2
4
57
Joseph Allen
@j_g_allen
·
1h
2. Not all masks are created equal N95/KF94/KN95 > surgical > cloth Here's my 90-second explainer from last winter
Quote Tweet
Joseph Allen
@j_g_allen
· Jan 27
Confused about N95, KF94, KN95, double-masking? You're not alone. Here is my 90-second explainer. Thanks to @GreaterBoston and @jimbraude for having me on.
40.5K views
0:00 / 2:15
1
20
75
Joseph Allen
@j_g_allen
·
1h
3. Cloth masks work, just not as well as high filtration masks --> a 50% effective mask reduces inhaled dose by...50% --> when two people where this level mask, the combined efficacy is 75% It's wrong to say these "don't work"; correct to say they are "less effective" than N95
6
10
90
Joseph Allen
@j_g_allen
·
1h
4. Surgical masks work I cringe when I see 'experts' say these masks leak so they don't work. Yes, some aerosol escapes out the side, but direction of airflow matters. Reducing the plume in the speaker's cone of emissions as they directly interact with others is key. And...
Joseph Allen
@j_g_allen
·
1h
...in places with good ventilation and filtration, these 'escaped' aerosols out the side of the surgical mask dilute further before reaching someone. This is the exact situation in hospitals. So...
1
2
74
Joseph Allen
@j_g_allen
·
1h
...when someone say surgical masks don't work in hospitals, they're ignoring the benefit of reducing the aerosol jet in front of the person and thinking of PPE in isolation, ignoring airflow dynamics in the space. N95s better? Sure, and should be norm for high-risk areas.
2
2
70
Joseph Allen
@j_g_allen
·
1h
5. The benefit of mask depends on the 2 Fs: filtration and fit Most spend their time focused on filtration, but fit is critical. I wrote on this in April *2020*. (You've heard of the 'Rainbow Passage' and 'user seal check', right? RIGHT??)
statnews.com
Without training, N95 masks may not protect workers on the Covid-19 frontlines
Firefighters aren't given a mask and helmet and sent into burning buildings without first being trained how to use the equipment to protect themselves. We should be doing the same thing for health...
2
7
57
Joseph Allen
@j_g_allen
·
1h
6. There is a hierarchy of controls PPE is what we use as last resort. Note it is the 'least effective' control. Early in pandemic, we needed all. The vaccines moved us up the hierarchy. Masks were necessary as the bridge to the vaccines.
3
6
64
Joseph Allen
@j_g_allen
·
1h
7. Set control strategy (eg, masking) based on risk Two key risk factors are vax status and age. We continue to ignore this when setting control strategy, and instead opted for 'one size fits all'.
Quote Tweet
Joseph Allen
@j_g_allen
· Nov 30
Two of the most important determinants of COVID-19 risk are age and vax status. Imagine ignoring this when analyzing data, offering policy advice, setting control strategies... Source: CDC
2
3
39
Joseph Allen
@j_g_allen
·
1h
Joseph Allen
@j_g_allen
·
1h
This is why I didn't write about everyone needing an N95 until winter 2021. In my assessment, 3-layer or surgical masks were fine for the risk we faced. Alpha changed this for me. (I brought back in the 'Rainbow Passage' and 'user seal check' (fit!))
washingtonpost.com
Opinion | Everyone should be wearing N95 masks now
With better masks, essential workers could have hospital-grade protections. What's stopping us?
3
7
42
Joseph Allen
@j_g_allen
·
1h
Quick nod to
@AbraarKaran
@RanuDhillon
@sri_srikrishna
who have been steadfast in calls for N95s since early on. Here they are in June 2020:
hbr.org
We Need Better Masks
Right now, it’s our best option to contain the virus and revive the economy.
1
4
37
Joseph Allen
@j_g_allen
·
1h
For me, I updated my recs on masks again once vaccines were widely available, to account for the change in risk to those who are vaccinated (and still recommended masks for unvaccinated)
Quote Tweet
Joseph Allen
@j_g_allen
· Dec 27
If your playbook and recommendations have not already accounted for this, they’re out of date. #2022Playbook twitter.com/scottgottliebm…
1
2
26
Joseph Allen
@j_g_allen
·
1h
Side note: On masks (and all controls), I think there is a danger of being on 'red alert' all the time. Pandemic is not like a hurricane where event happens and you march steadily toward recovery. Rather, it ebbs and flows. Controls should, too.
Quote Tweet
Joseph Allen
@j_g_allen
· Dec 21
When risk was low (eg, NE in spring, summer, fall), so many stayed on DEFCON1. (Remember folks advocating for vaxxed to mask in VT when hosp <1/100,000 b/c they relied on CDCs flawed metrics which said ‘substantial risk’??) Set us up for failure this winter. Control fatigue.
4
11
57
Joseph Allen
@j_g_allen
·
1h
8. One-way masking is fine If you're vaccinated, and boosted, and wearing an N95, that's as low risk as anything in your life, *regardless of what anyone around you is doing*.
https://washingtonpost.com/opinions/2021/12/15/our-playbook-fight-covid-19-is-outdated-here-are-10-updates-2022/…
6
22
103
Joseph Allen
@j_g_allen
·
1h
9. For the newly "N95 or bust" crowd, I have something that will blow your mind. You know there are even better masks than N95s, right? RIGHT?? Google "N100" Cheers! -end-
16
5
97
https://www.hsph.harvard.edu/joseph-allen/
Joseph Allen
@j_g_allen
I see a lot of people - on both "sides" - making simple mistakes about masks. I've studied PPE, taught PPE, and overseen PPE programs, including teams implementing fit testing in hospitals, long before covid. A thread
8:03 AM · Dec 29, 2021·Twitter Web App
143
Retweets
30
Quote Tweets
277
Likes
Tweet your reply
Reply
Joseph Allen
@j_g_allen
·
1h
Replying to
@j_g_allen
1. Masks work It's basic physics.
nytimes.com
Masks Work. Really. We’ll Show You How (Published 2020)
A visual journey through the microscopic world of the coronavirus shows how masks provide an important defense against transmission.
3
10
77
Joseph Allen
@j_g_allen
·
1h
I made one of the earliest calls for universal masking, for that reason. April 2, 2020
washingtonpost.com
Opinion | You need to wear a mask. Here’s how.
Everyone should be covering their faces. Here's how to do it correctly.
2
4
57
Joseph Allen
@j_g_allen
·
1h
2. Not all masks are created equal N95/KF94/KN95 > surgical > cloth Here's my 90-second explainer from last winter
Quote Tweet
Joseph Allen
@j_g_allen
· Jan 27
Confused about N95, KF94, KN95, double-masking? You're not alone. Here is my 90-second explainer. Thanks to @GreaterBoston and @jimbraude for having me on.
40.5K views
0:00 / 2:15
1
20
75
Joseph Allen
@j_g_allen
·
1h
3. Cloth masks work, just not as well as high filtration masks --> a 50% effective mask reduces inhaled dose by...50% --> when two people where this level mask, the combined efficacy is 75% It's wrong to say these "don't work"; correct to say they are "less effective" than N95
6
10
90
Joseph Allen
@j_g_allen
·
1h
4. Surgical masks work I cringe when I see 'experts' say these masks leak so they don't work. Yes, some aerosol escapes out the side, but direction of airflow matters. Reducing the plume in the speaker's cone of emissions as they directly interact with others is key. And...
Joseph Allen
@j_g_allen
·
1h
...in places with good ventilation and filtration, these 'escaped' aerosols out the side of the surgical mask dilute further before reaching someone. This is the exact situation in hospitals. So...
1
2
74
Joseph Allen
@j_g_allen
·
1h
...when someone say surgical masks don't work in hospitals, they're ignoring the benefit of reducing the aerosol jet in front of the person and thinking of PPE in isolation, ignoring airflow dynamics in the space. N95s better? Sure, and should be norm for high-risk areas.
2
2
70
Joseph Allen
@j_g_allen
·
1h
5. The benefit of mask depends on the 2 Fs: filtration and fit Most spend their time focused on filtration, but fit is critical. I wrote on this in April *2020*. (You've heard of the 'Rainbow Passage' and 'user seal check', right? RIGHT??)
statnews.com
Without training, N95 masks may not protect workers on the Covid-19 frontlines
Firefighters aren't given a mask and helmet and sent into burning buildings without first being trained how to use the equipment to protect themselves. We should be doing the same thing for health...
2
7
57
Joseph Allen
@j_g_allen
·
1h
6. There is a hierarchy of controls PPE is what we use as last resort. Note it is the 'least effective' control. Early in pandemic, we needed all. The vaccines moved us up the hierarchy. Masks were necessary as the bridge to the vaccines.
3
6
64
Joseph Allen
@j_g_allen
·
1h
7. Set control strategy (eg, masking) based on risk Two key risk factors are vax status and age. We continue to ignore this when setting control strategy, and instead opted for 'one size fits all'.
Quote Tweet
Joseph Allen
@j_g_allen
· Nov 30
Two of the most important determinants of COVID-19 risk are age and vax status. Imagine ignoring this when analyzing data, offering policy advice, setting control strategies... Source: CDC
2
3
39
Joseph Allen
@j_g_allen
·
1h
Joseph Allen
@j_g_allen
·
1h
This is why I didn't write about everyone needing an N95 until winter 2021. In my assessment, 3-layer or surgical masks were fine for the risk we faced. Alpha changed this for me. (I brought back in the 'Rainbow Passage' and 'user seal check' (fit!))
washingtonpost.com
Opinion | Everyone should be wearing N95 masks now
With better masks, essential workers could have hospital-grade protections. What's stopping us?
3
7
42
Joseph Allen
@j_g_allen
·
1h
Quick nod to
@AbraarKaran
@RanuDhillon
@sri_srikrishna
who have been steadfast in calls for N95s since early on. Here they are in June 2020:
hbr.org
We Need Better Masks
Right now, it’s our best option to contain the virus and revive the economy.
1
4
37
Joseph Allen
@j_g_allen
·
1h
For me, I updated my recs on masks again once vaccines were widely available, to account for the change in risk to those who are vaccinated (and still recommended masks for unvaccinated)
Quote Tweet
Joseph Allen
@j_g_allen
· Dec 27
If your playbook and recommendations have not already accounted for this, they’re out of date. #2022Playbook twitter.com/scottgottliebm…
1
2
26
Joseph Allen
@j_g_allen
·
1h
Side note: On masks (and all controls), I think there is a danger of being on 'red alert' all the time. Pandemic is not like a hurricane where event happens and you march steadily toward recovery. Rather, it ebbs and flows. Controls should, too.
Quote Tweet
Joseph Allen
@j_g_allen
· Dec 21
When risk was low (eg, NE in spring, summer, fall), so many stayed on DEFCON1. (Remember folks advocating for vaxxed to mask in VT when hosp <1/100,000 b/c they relied on CDCs flawed metrics which said ‘substantial risk’??) Set us up for failure this winter. Control fatigue.
4
11
57
Joseph Allen
@j_g_allen
·
1h
8. One-way masking is fine If you're vaccinated, and boosted, and wearing an N95, that's as low risk as anything in your life, *regardless of what anyone around you is doing*.
https://washingtonpost.com/opinions/2021/12/15/our-playbook-fight-covid-19-is-outdated-here-are-10-updates-2022/…
6
22
103
Joseph Allen
@j_g_allen
·
1h
9. For the newly "N95 or bust" crowd, I have something that will blow your mind. You know there are even better masks than N95s, right? RIGHT?? Google "N100" Cheers! -end-
16
5
97