Just as I advocated for mask use when needed, I'm going to join @j_g_allen in advocating for ending mask rules when no longer needed. In my mind, that's after kids 5-11 have a chance to get vaccinated. /1
My 10-yo will get vaccinated as soon as possible, not because I'm particularly worried about her getting Covid-19 but because I'm worried about her *spreading* it. /2
With the normalization of mask wearing in the US, I hope that people will feel comfortable wearing them or not wearing them as it makes sense (not for political reasons). /3
And yes, mask rules are helpful when/where hospitals are overwhelmed, community transmission is high, if new surprise comes along, like Delta. Not sure about tying it to vax rate because of correlation between anti-vax and anti-mask. /4
I knew I would take some heat about this, but we need to start having this conversation because we're not going to mask forever and we're not going to get to zero risk. /5
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Tang & I wrote about updating transmission routes to inhalation, spray, and touch, following up on suggestions by Yuguo Li and @Don_Milton. academic.oup.com/cid/advance-ar… /1
"Current infection-control guidelines subscribe to a contact/droplet/airborne paradigm that is based on outdated understanding. Here, we propose to modify and align existing guidelines with a more accurate description of the different transmission routes." /2
"This will improve the effectiveness of control measures as more transmissible variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerge." /3
"The phenomenon of low risk outdoors and high risk indoors deserves some explanation. This is probably the most important observation in this pandemic. There is a simple explanation: dilution." /2
"For an ideal expired jet from a person breathing at rest, at a distance >1 m, there is >10-fold dilution from surrounding air because of...entrainment. If the surrounding air is totally free from infectious virus, as it is outdoors, the concentration beyond 1 m is very low." /3
I wrote about applying what we've learned from Covid-19 to the flu. nytimes.com/2021/10/19/opi… Cleaner air (ventilation & filtration) is a "powerful tool for reducing the risk of Covid-19 transmission, & it should be embraced more thoroughly during this pandemic and to reduce flu"/1
We inadvertently squashed the flu last year, probably thanks to our interventions against Covid-19 combined with our pre-existing immunity to flu. @Lakdawala_Lab showed that this factor is a barrier to airborne transmission. journals.plos.org/plospathogens/… /2
@Lakdawala_Lab "I hope that Covid-19 has catalyzed a shift in thinking about the air we breathe. You wouldn’t drink a glass of water full of pathogens, chemicals and dirt. Why should we put up with breathing contaminated air?" /3
Our paper examining the origins of the erroneous 5 μm cutoff for aerosols v. droplets and the 6' rule is now published. One of my fave interdisciplinary collaborations yet, involving rhetoric, history, aerosol science, fluid dynamics. royalsocietypublishing.org/doi/10.1098/rs… /1
With @katierandall@EThomasEwing@jljcolorado Bourouiba. The 5-μm error came from conflation of how droplets/aerosols move through the air with where they deposit in the respiratory tract. The 6' rule came from misinterpretation of studies with bacteria settle plates. /2
These became entrenched through "citogenesis," which I would define as propagation of mis-cited work. /3 xkcd.com/978/
We did some more testing yesterday and updated tinyurl.com/VTkidsmasks with a column dedicated to efficiency as worn. Added results for KF94/KN95s received from @masknerd. Take homes: N95 clearly the best (small 3M Vflex 9105S), KF94/KN95s around 90%, most cloth masks ~60-80%. /1
Based on our testing and some new studies, we moved all cloth masks to the BETTER category and moved surgical + brace or surgical + cloth double masking to the BEST category, which also has KN95/KF94 (small-sized N95s may work for big kids). /3
Our new preprint led by Hawks and Duggal shows infectious virus emitted in air from hamsters (upper right) on days 1-2 but not later, even though RNA still there (lower right). biorxiv.org/content/10.110… /1
We used a condensation particle sampler with & without cyclone. Saw similar amounts of infectious virus, so it's mostly <8 μm.
8-μm particles can float around for at least 13 minutes, and the smaller ones stay in the air for hours. /2
Sampling method does not exclude potential for resuspension from fur and ground, but there was more virus in oral swab & nasal wash than on fur. Either way, though, there's infectious virus in the air. /3