Thread by @MonicaGandhi9

TRANSMISSION routes - a PROPOSAL. Have seen all the discussion on aerosol spread of a pathogen (defined as small particles that can linger in air & ventilation most important) vs droplet spread (larger particles with gobs of spit, distance important) and I propose new definition

Which is to define a pathogen (e.g. SARS-CoV-2, TB, etc.) by the best way to keep people safe, best strategies for mitigation instead. We proposed a complementary 3-way non-pharmaceutical (NPI) triangle in this @TheLancetInfDis article.
thelancet.com/journals/lanin…

Masks, distancing, ventilation being most important NPI strategies but relative importance of each being defined by (traditionally) aerosol vs droplet. Why not instead of define each pathogen by relative importance of mitigation strategies? For instance, ventilation important

for TB & SARS-CoV-2 because both can have very small particles which dissipate readily in outside air (heat, humidity also matter). However, "dogma" says that TB can only be blocked by N95 masks although this study shows us surgical face masks on MDR TB
atsjournals.org/doi/full/10.11…

patients (when outside air piped to guinea pigs) protected those guinea pigs (even when MDR TB patients just wearing surgical not N95 masks). So, this distinction is not always clear cut. And @linseymarr and I show in an article from November, along with @CDCgov in February, that

a surgical mask + cloth mask OR a cloth mask with a filter pocket inside it worked ~as well as an N95. So, why not instead define - of the 3 most important mitigation procedures for a respiratory pathogen (masks, distancing, ventilation), which one tugs
cell.com/med/pdf/S2666-…

for #COVID19, the data on outside transmission is very clear. So, outside - no masks unless closely packed together in which case some droplet spread can occur. Inside, masks (until we get to certain vaccination rate - 70% 1st dose + 1.8/100K cases or whatever metric chosen) &

a corner of the NPI triangle in the right direction. So, for instance, if ventilated (outside, window open), no masks for mitigation but inside needs masks for mitigation (until we get to 70% 1st dose vax rate + 1.8/100K cases as possible metric to stop masking indoors).

This is possible framework to bring us all together on definitions of mitigation strategies & relative importance of each vs defining by aerosol vs droplet as non-continuum; welcome thought paper on this with someone after Aug. Speaking of, going off twitter until Sat to work.

And, importantly, if you look at our NPI triangle, the susceptibility of the host is inside the triangle. This is why the WHO does not advocate for masking young children & neither should we. Everything becomes individualized mitigation instead of @onesizefitsall

Quoted in this well-done @medpagetoday article describing these distinctions between droplet & aerosol and how think we should go towards a mitigation strategy approach instead of a "size of particle" approach.
medpagetoday.com/special-report…