https://www.who.int/news-room/commentaries/detail/modes-of-t...
> In an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported.
(This is also a reason masks can be effective despite the virus particles being smaller than what masks can stop; you don't have to stop the particles, but the much larger drops they're contained within.)
I understand the distinction, but the terminology should be renamed imho, to something like "epidemiologist airborne". Because to the layperson it definitely is transmitted "through the air", implying again in everyday terms "airborne transmission".
e.g. read this : https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article
and look at the associated diagram:
https://wwwnc.cdc.gov/eid/article/26/7/20-0764-f1
Those people were NOT all within six feet of each other.
The German auto part plant paper also details transmission where nobody sneezed or coughed at a short business meeting.
As that study discusses, they were in the path of an air conditioner. The "six feet" thing is a rough estimate, not the Eleventh Commandment.
It's more complicated because there are actually 4 mechanisms that might stop a particle from getting through.
1. For particles bigger than the gaps, it does work like a net as most people expect.
2. For particular smaller than that but massive enough that they cannot change direction fast enough to follow the air stream they can miss turns of the air flow and get embedded in the fibers.
3. For even smaller particles they can get jostled around significantly by hits from gas molecules (like with Brownian motion). This can knock them into fibers where they can become embedded.
4. Some filters materials have an electrostatic effect that can attract and hold passing particles.
One of the reasons filters are commonly rated by their efficiency at 0.3 micron is that this is in the region where the filter is least efficient. For bigger particles, the gains from #2 and later #1 more than make up for #3 being irrelevant at those sizes. For smaller particular, the gains from #3 increase efficiency.
So you have the filter roughly getting worse down to the 0.3 micron ballpark, and then getting better as particles become still smaller, and at some point as you continue getting smaller it is going to get worse again. (I don't know where that final turn around is).
By contrast, measles has an rFactor of 17, because it is an aerosol. It is 6x more contagious. And as an aeorsol, simply breathing next to a person who is infected is enough for you to contract the virus.
Airborne is not the same as aerosol.
Put another way. If there is a person infected in a house hold with coronavirus, not everyone is guaranteed to get it, because it is only airborne.
If someone has the measles in a house hold, and there is no vaccine, then everyone will get it, because it is an aerosol.
> In an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported.
"They will not stay suspended in the air" means it's not airborne. An airborne disease is one that does stay suspended in the air.
It's recently been revised up to 5-6 [0], and mortality estimates reduced.
https://www.forbes.com/sites/tarahaelle/2020/04/07/the-covid...
The CDC paper [1] estimated that the R0 value may have been 5-6 in Wuhan, during lunar new year, and before the public was ware of the virus.
Alternatively, the R0 value is now <1 in the US and the spread is decreasing,
Evidence out of NY today says it’s possible 14% of the state has already been infected. That’d point to a pretty high value.
https://www.wxxinews.org/post/random-test-finds-nearly-14-ny...
IF new cases today are less than yesterday, the R0 must be <1 one incubation period ago. That doesn't mean that R0 wasn't different a month ago, or will be the same a month from now.
That's a big if. We don't have enough testing in place to determine that currently. The reported number of cases and the actual number of cases are not the same right now.
Positive cases have stayed roughly the same since April 4th while testing increased. For R0 to be greater than 1, we would have to be worse at testing.
https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/test...
(Direct link: https://www.cdc.gov/coronavirus/2019-ncov/images/lab-specime...)
We've been basically flat since mid-March.
I think the point still stands unless you think we are identifying a lower proportion of infections
I do. https://www1.nyc.gov/assets/doh/downloads/pdf/imm/covid-19-d... indicates many areas of NYC are seeing more than 57% positive results; that likely indicates we're not even scratching the surface. We're simply not that good at identifying who to test.
The estimated r0 of 2/3 is hilarious. less contagious than sars eh? No amount of down-voting me or cdc papers is going to convince me of that.
https://web.mit.edu/jeffrey/harris/HarrisJE_WP2_COVID19_NYC_...