This seems pretty flaggable.

I understand that, but I think you’re missing the bigger issue. Let’s say five years from now they’re on the fifth new booster (optimistically, since this one took longer than a year to come out), will you have had to complete all 6+ earlier boosters in sequence before you can get the latest one? Surely at some point it’s not a reasonable assumption to think that everyone has diligently gotten the latest shots, like clockwork. Eventually the shots have to be able to work independently, right? Again, we seem to be able to pull off a new flu shot every single year...