Your second post doesn't seem to match up with the weird riddle that is your first post though.David Williams wrote: ↑Mon Apr 06, 2020 12:24 pmI think it's valid.
Suppose it was established that having a meal in a restaurant with an infected person gave you a 50% chance of being infected. Sheer chance, different immune systems, whatever. How many people would you expect to be infected if that person spent the same amount of time at a speed-dating event, sitting across a table from 20 different people? It could be as many as ten, if it takes only minimal contact. It could be none, if there's threshold that has to be exceeded.
When it comes to relaxing lockdown it matters a lot. On one scenario restaurants remain shut. One infected waiter is likely to infect half the customers. On the other it's perfectly safe to open restaurants to groups comprising members of the same household, so long as the tables are 2 metres apart (which is virtually impossible, but you get my point).
There was an article in New Scientist discussing whether your amount of exposure to the virus affects how badly you get the disease - they weren't sure. Though in the sample size of one, that Chinese doctor who died was quite young and it was suggested that he might have got it worse because he'd been more exposed to it.
But anyway, I think it does take a certain number of the viruses for it to take hold at all, so prolonged exposure might be necessary unless they actually cough in your face - which would contrast with something like radioactive decay, where the "event" can just happen at any time with a certain half life.
Based on this, I'd guess that if you have a 50/50 chance of infecting someone at a meal, then out of 20 people that all spend 1/20 of that time with you, you'd infect an average of less than 10. I don't really know though. And an accidental cough or sneeze could mess this right up (though you'd probably cover your mouth).