Originally Posted by trueblu

The Amoy garden case (which not everyone 100% takes at face value, but it made a superstar of the HK physician who came up with the idea) was that flushing of the toilet, due to poor drainage, caused a 'jet stream' (for want of a better word) across the complex to the other side. This was with a person with severe diarrhea who was expelling billions (trillions?) of infectious particles per loo visit. That's not quite the same as general airborne risk. I remember that for the next few months we (I was an infectious diseases physician in training and doing my PhD at the time) all chose to 'close the lid' on the loo, just in case, and still do, to this day when 'symptomatic'.

With regards to the cruise ship...I'm not convinced this is one single outbreak, but more probably a limited chain of transmission: patient zero to a cluster of 5-10 people, each of which then infected a similar number of people before the alarm was raised. Remember that although there is talk of incubation period of 14 days, this is the outlier time-line. Most infected patients with coronavirus (typically) start showing symptoms within 2-6 days, with some as early as 1 day, and the vast majority by 10-11 days with a few stragglers. Some of the early data on nCoV suggests a similar pattern, but with perhaps a sl. fatter tail.

The cruise ship also may shed light on why we are seeing relatively limited chains of transmission outside of China: a) close quarters/ crowding is a major risk factor, b) hand to mouth/ nose transmission may be a more significant factor than inhalation risk [can't fully parse that one out], c) age-related?? Are elderly people not only more susceptible but more likely to transmit??

I hope that if they do let people off the ship after 14 days, they insist on being able to track down every individual: pax and crew, for another week or so and perhaps check-in with each of them by phone afterwards. Otherwise, this ship may be the single biggest source of potential onward transmission outside mainland China!!

tb

tb