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Comment by marcelsalathe | Hacker News Reader

Your 80% number is misleading. There is no good data on that. Flu has long been thought to be mainly transmitted through droplets, which fall to the ground quickly, rather than being dispensed in the air, being able to travel large distances (which would be truly airborne). If anything, the latest data suggest that we have actually underestimated the airborne route (relative to the droplet route).

Yes, a pandemic can occur even if the pathogen is not transmitted through there air - see HIV/AIDS.

Airborne and droplet spread make for fast spreading and hard to control epidemics. If something spreads through bodily fluids only, it's easier to do contact tracing and put the right measures in place. I think that's what people want to highlight if they say that Ebola is not airborne.

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> Flu has long been thought to be mainly transmitted through droplets, which fall to the ground quickly, rather than being dispensed in the air, being able to travel large distances (which would be truly airborne).

Actually, there was a study earlier this year[0] which showed, with better data and more rigorous treatement of the fluid dynamics, dropplets can travel much farther than previously thought. [1] has a summary of the research, in case the article is not available. But their basic conclusion is that, depending on the size, droplets can travel up to 200 times farther than previously thought, because they are carried along with the "cloud" associated with the sneeze.

[0] http://journals.cambridge.org/action/displayAbstract?fromPag...

[1] http://www.huffingtonpost.com/2014/04/09/sneeze-cloud_n_5110...

I'm basing that number on a paper I read a while ago that estimated the infection channels from a variety of experimental and epidemiological data. I can't find the original article with a quick search, but there are plenty of other papers that show how efficient the hand-contact mechanism is. For example:

http://www.ncbi.nlm.nih.gov/pubmed/205151

In that study, 11 of 15 hand-contact exposures to a rhinovirus led to infection, which is not 80%, but it's within the margin of error. Notably, it was almost as good as large-particle aerosol exposure at spreading the virus.

But yes, the important point is that you don't need an airborne virus for a pandemic. Every virus is different, but there's this public fixation on "airborne" transmission that is a bit of a red herring. Ebola is doing just fine without it.

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