In what way is it a real thing? Antibodies are not immunity. It doesn't really mean anything if antibodies don't evolve as new variants are encountered. Francis's 60 year-old paper is just something vaccine researchers have latched onto to blame the natural immune system for not being as artificially "rewrite-able" as they want it to be.
It's not too complicated - instead, you just captured why the theory of OAS doesn't make sense.
Brian - you mean why OAS doesn't make sense to explain this particular result? Because the phenomenon in general is a real thing, after all.
In what way is it a real thing? Antibodies are not immunity. It doesn't really mean anything if antibodies don't evolve as new variants are encountered. Francis's 60 year-old paper is just something vaccine researchers have latched onto to blame the natural immune system for not being as artificially "rewrite-able" as they want it to be.