On a personal level it's gonna be either 100% or 0%. You either got severe disease, or you didn't.
You can't extrapolate a population-level percentage from a single data point. Luckily, we've got information on hundreds of thousands of deaths, millions of hospitalizations, and billions of shots.
You can't get 15% of a case of severe COVID. At a personal level, the vaccine either worked at preventing it, or it didn't. We can compute a population-level probability of those two scenarios for you, but you can't really say "15% effective, after 2 jabs, for me personally".
See https://vinayprasadmdmph.substack.com/p/vaccine-effectivenes...
Those "frickin" statistics? Or which ones?