I think if you're less than a year post-chemo you should ask your MO. Otherwise, if you're blood is back to normal (my WBC is on the low end of normal but my MO says that's still fine), a shot is probably a good idea. especially if, like me, you're likely to be exposed to sick students who love to come into my airless office and explain why they were too sick to come to class in the midst of flu season (why they don't see this as an appropriate occassion to use the phone or email is beyond me--it's as though they think I need to se them to believe them but I don't WANT to see them and don't want their germs in my office!)