The nasal vaccine - FluMist - is only effective in children. Adults have to get the jab.
Again, today's flu vaccines are made from inactive, killed virus. You cannot get the flu from the jab! What can happen, however, is that you contract the virus before the jab has a chance to work - it takes about a fortnight. OR, you could already have the virus at the time you get the jab - influenza has a long incubation period.