We already knew that about cruises.

> However, it does not explain why we haven't heard of flu outbreaks in cruises before this coronavirus

We have, actually, but we don't hear about it much, because, except with the scrutiny occurring during this COVID-19 outbreak, which led to media exposure for a cruise ship flu outbreak [0], cruise ships are only required track and report when gastrointestinal disease hits a certain threshold, not respiratory ailments. [1]

[0] https://www.baltimoresun.com/health/bs-hs-royal-carribean-fl...

[1] https://www.cdc.gov/nceh/vsp/surv/gilist.htm

Anecdotally I hear about it almost every time the topic of cruises come up on Reddit or other social media. I just don't think its particularly newsworthy so it isn't making headlines. Cruise ships and Conventions are pretty similar in the sense that people just get notoriously sick after attending is my understanding.

> Kentaro Iwata, an infectious diseases expert at Kobe University who visited the ship, strongly criticised the management of the situation in two widely circulated YouTube videos published on 18 February.[36][37][38][39] He called Diamond Princess a "COVID-19 mill".[40] He said that the areas possibly contaminated by the virus were not in any way separated from virus-free areas, there were numerous lapses in infection control measures, and that there was no professional in charge of infection prevention—the bureaucrats were in charge of everything.

As I understand it, the message from CDC etc is, roughly: It's transmitted through droplets coughed or sneezed from one person that then end up through common touching of not-cleaned surfaces and thence into the body through face-touching.

My gut feel is that if that's how transmission occurs, we shouldn't see infection spread between large numbers of people who were simply present in the same room as each other for a few days.

Which makes me wonder if all the hand washing is just "Epidemiology Theater".

People cough and sneeze all the time, even healthy people, and the droplets of saliva from that land on surfaces that other people touch and then they touch their faces, rub their eyes and pick their noses. So the virus will spread in the air and also by transmission onto mucus membranes from your hands. It’s not airborne but there is droplet transmission. The danger is relatively small if people don’t touch, like shaking hands, hugging or kissing, and if surfaces are wiped down with disinfectants regularly and everyone washes their hands but that does not describe most people’s experience of being in a room with other people for a few days.

I don't think the hand-washing is epidemiology theater, in part based on this thread: https://twitter.com/PalliThordarson/status/12365493051895971...