They only protect against their best guess predictions of what will be the most prominent strain. Other strains may emerge as more prominent and aren't protected against. I'd wager you got a different strain.
And I don't mean to be obnoxious, but isn't it since 2006 that your health has declined in other areas (diabetes, even more weight gain, etc?) I'd say that is more probably the cause of the failure in your immune system than a singular vaccine for an unrelated illness.
And I don't mean to be obnoxious, but isn't it since 2006 that your health has declined in other areas (diabetes, even more weight gain, etc?) I'd say that is more probably the cause of the failure in your immune system than a singular vaccine for an unrelated illness.