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Nearly tears of joy seeing new paper in medical journal with correct analysis and interpretation of aerosol transmission: https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30323-4/fulltext See thread for summary of main points. /1
Where we have been: "Current infection control policies are based on the premise that most respiratory infections are transmitted by large respiratory droplets—ie, larger than 5 μm— produced by coughing and sneezing, then deposited
onto exposed fomite or mucosal surfaces." /2
onto exposed fomite or mucosal surfaces." /2
Pathogens (e.g., M. tuberculosis, influenza, RSV, rhinovirus, many more) are consistently found in small aerosols <5 microns and if size-resolved data available, in much higher amounts than you would expect based on aerosol or droplet volume. /2
"There is no evidence to support the concept that most respiratory infections are associated with primarily large droplet transmission. In fact, small particle aerosols are the rule, rather than the exception, contrary to current guidelines." /3
"The logic that transmission within close proximity
defines respiratory droplet spread is fallacious, as small
particle aerosols are in the highest concentration close to
patients and dissipate with distance." I want to ask the author if I can hug him. /4
defines respiratory droplet spread is fallacious, as small
particle aerosols are in the highest concentration close to
patients and dissipate with distance." I want to ask the author if I can hug him. /4
"The variability of transmission among respiratory pathogens appears to be less dependent on the physical
particle size emitted by the diseased person, as current
guidelines suggest, but more by biological factors such
as the size of the emitted inoculum," /5
particle size emitted by the diseased person, as current
guidelines suggest, but more by biological factors such
as the size of the emitted inoculum," /5
"the ability of the pathogen to survive desiccation and other stresses of aerosolisation and airborne transport, and environmental factors such as air movement, temperature and humidity, and host defences." More love for the author and why I have been studying humidity! /6
"A major limitation to much of the data on infectious aerosols of viruses is the reliance on PCR findings; few studies have evaluated viability using cell cultures or other methods. Viability itself can be difficult to assess." /7
"These multiple factors, as well as inherent physical inefficiencies of air samplers, suggest that most infectious aerosol data are probably underestimates of the exposures to health-care workers." ...and to others. Hallelujah! /8
The review of ambient measurements missed our paper from 2011, "Concentrations and size distributions of airborne influenza A viruses measured indoors at a health centre, a day-care centre and on aeroplanes" https://pubmed.ncbi.nlm.nih.gov/21300628/ , but we didn't cover hospitals. /9
HT @kprather88 and @EricTopol
