The Japanese seem to think that the virus particularly spreads in clusters, places where the following three conditions are met simultaneously: (1) closed space with poor ventilation, (2) crowded with many people and (3) conversations and vocalization in close proximity (within arm's reach of one another). This is explained in this
expert opinion document that states: "overall, approximately 80% of the domestic confirmed carriers, regardless of the severity of their symptoms did not infect others"
Exactly, this is pretty much what I had worked out - maybe these factors:
1. Lots of people together indoors milling about and talking.
2. Recirculating air maybe through air conditioning systems.
3. Lots of people touching surfaces while eating or drinking.
This would explain spread on cruise ships, airport lounges, aeroplanes. It may apply to supermarkets but without the talking maybe much less.
Another factor that might be
even more crucial is a pattern of behaviour in which individuals are in this sort of environment
at least once a week - maybe these people, who seem to be overrepresented.
1. Politicians, their advisors and spouses
2. Film and music stars
3. Religious worshippers (Korea)
The point here is that if you do this once a week you are likely to spread your virus to others during an initial asymptomatic phase a week after catching it.
Perhaps all that we really need to do is to stop everyone from being in a crowded space ONCE A WEEK or more often. That would mean banning tube travel, pubs and restaurant meals, conferences and airports. Everything else could carry on as normal.