Regarding elections: I'd say it is likely that these will be postponed. Not just in the US but everywhere in the world. You can't have a change of government in a crisis this large. Even if it is possible to organise a vote then whatever candidates say or promise will be lost in the noise from the Corona virus.
FWIW, I seriously doubt that the election in the US will be delayed under any circumstances. I'm sure that even in Europe you've seen the hatred and bitterness and the numerous false accusations and even an attempted impeachment that had been directed at Donald Trump and many others in his administration. ANY attempt to delay the elections will be seen by his enemies as an attempt to seize power and there's no telling where that will lead. OTOH It's past time that the US implemented a modern secure voting system that wouldn't require everyone to show up in person. The banks and other businesses have secure online and telephone systems, it's about time that our voting system was as secure as those systems.
We do have a process for mail-in voting. I expect that they will resort to that system for this election but you can be sure that some group will shout and scream that mail-in voting is unaffordable and racist and that it will disenfranchise them.
It's a big unknown. I was looking around at some numbers...
California cast over 14 million votes in the last general election and about 58% were absentee ballots (mail in votes).
https://www.sos.ca.gov/elections/historical-absentee/ The USPS delivers ~ 187.8 million pieces of First-Class Mail per day.
https://facts.usps.com/one-day/But, as was noted by @james_s, some states do not have mail-in voting and still others don't have mail-in voting without an excuse (and there are lists of acceptable excuses).
I don't know how difficult/legal it would be to change State voting procedures in just a few months.
Five states have delayed primaries so far. In Ohio, a judge disallowed the change and the Governor went ahead and did it based on a State of Emergency declaration. Primaries are basically smaller elections that decide who is going to running in the General election. Being delayed is, of course, not being cancelled.
If we were ever to institute and enforce law prohibiting large number gathering (can you do that in a state of emergency? don't know but probably, I would think so). If so, you would be running head-to-head with free elections and that would not go over at all. So, it seems like you would have to, at least, provide mail-in voting.
It is a big time mess that could be around the corner (~7 months).
I was looking at the daily new case data for South Korea (from
https://www.worldometers.info/coronavirus/country/south-korea/)
and thinking about how it could be used as a test for the predicted infection rates in the Brit report (the earlier posted figure), but a) there is not enough data yet and b) I don't know the status of the NPI there.
I'm sure that these types of examples will be watched carefully. I'm also confident that others are going to produce their models and we will look for agreement/departure from the Brit report predictions. In fact, since I assume that such has been going on in the US for a while, I am a little concerned that the US has not come out with anything refuting (or supporting) the report's predictions. Maybe that will be in tomorrows news.
I still like the idea of harvesting antibodies from millennials - you know, social conscience and all that