I can't decide what to do about the shingles vaccine. I'm 50, so I could take it now, but it doesn't last very long (5-10 years?), and there's no booster later. So do I take it now, and then find myself at risk again when I'm older and possibly in worse health? Or wait a few years so that I'm protected when I'm older? My doctor doesn't seem concerned either way when I've asked him.