I'll believe it when I see actual data beyond safety and immunological analysis beyond antibody responses (historically an easy measure but poor proxy for overall efficacy). Universal vaccines for influenza have been a highly sought after outcome for decades with none of them actually working or, in some cases, new science showing the rationalizations behind some candidates no longer holding up as sound reasoning.

But if it does work out, then this would be a major breakthrough that could/maybe be applied to other virus families.