Large scale studies are understanding how quickly immunity wanes from both immunization and convalescence (ie, prior infection).
In the former case, booster shots can restore adequate levels of antibodies.
In the latter case … what … COVID parties ??
That’s a major issue.
It’s also an issue to establish when a person with convalescent immunity was originally infected. The only thing we could do at this point, AIUI, is regularly monitor their antibody levels.
Which is likely an impractically resource-intensive solution to placate a relative few with relatively weak objections to just getting vaccinated (, too).