... the vaccine only has a 50-50 chance of working???

My dad had shingles and it was awful - I think he's still dealing with the pain, it's just dwarfed by the pain he has from other things right now. He's lucky that we were on vacation in Austria when it struck him and he was able to get great medical care to keep it from blinding him - even though changing his flight and going home early in that kind of pain can't have been much fun. But vaccines aren't without risk, and 50-50 just doesn't seem worth it to me.