Human-to-human (h2h) spread of the new coronavirus detected in Wuhan.A few thoughts.
To say that there is *no* h2h during the discovery phase of an emerging disease is using language that is too strong, possibly leading to doubt in the narrator/narrative or to false security.

It makes sense that a virus that can infect a human when acquired from an animal source, will be able to infect a human if projected from a human source. It may not do that frequently but is quite possible it *can* do that under suitable circumstances.

If the virus replicates in the lower airways rather than the upper airways like a common cold virus (think of the larynx as a boundary line), it can be less easy for us to breath, cough, drip or sneeze it out. So spread is more limited. But far from impossible.

As yet, we know ZERO about whereabouts in the human (or presumed intermediate animal or reservoir animal host) body this virus replicates. Routinely, when testing for respiratory viruses, we sample from the URT. LRT samples will are recommended by WHO for more serious cases.

Some have said (perhaps a little late) that we should not be surprised to see some h2h spread. That is facilitated by those suitable circumstances. They include close contact (caring for sick person), shared environments (shared & contaminated surfaces) & prolonged contact

These 3 things all occur among families and this is where we see an otherwise poorly h2h transmitting virus jump to other humans. And it's where we've seen 2 family instances identified thus far. The same occurs with MERS and MERS-CoV.

We can also see h2h in healthcare facilities if the healthcare workers get exposed before instituting suitably protective protocols. They have close and prolonged exposure to patients. The reason we may not have seen it in Wuhan could be very good use of such protocols.

Infection via close contact and contact with contaminated surfaces are pretty self-explanatory. Prolonged exposure may occur through *repeated* exposure to small doses of virus such that our immune system cannot contain the virus.

So should you be worried if you live somewhere else? Not at this stage with the info we have to hand. That isn't a lot of info though and things may change. What we know is that the virus isn't causing widespread pneumonia. Could it be causing milder respiratory illnesses? Maybe.

It seems like something delivered the virus to human airways probably from animals at the Huanan seafood (etc) market. That animal may be at one more other markets but remains unfound. There seems to be limited h2h associated with close contact.
Now we wait for more info.