The short answer is that it depends on the vaccine so it varies. Some vaccine trials require a booster shot several weeks after the initial dose.
Coronaviruses trigger a relatively poor immune response so if a booster shot provides reasonable protectionfor around 12 months that would be a good outcome in my uninformed opinion.
As for the end game. Who knows? I can't say whether or not a child with COVID related heart inflammation (and perhaps few if any other symptoms) will encounter heart problems when they are 50 or 60. We just don't know except to say that the more scar tissue that is left behind the worse the prognosis.
Economically we are f&c&ed IMHO. CBs can deliver helicopter money forever if required but what happens when they do?
