They are no long made with a live virus and they do not give you the flu anymore. It takes about 2 weeks to become protected and there are flu viruses out there that are not included in the shot.
I had an allergic reaction after getting my flu shot a few years ago and it was decided that the preservative was the problem. For the last 3 years I have gotten the vaccine without preservative and have had no problem. Sometimes you have to search out preservative free vaccine.
The flu is especially dangerous for older people as it can easily go into pneumonia. I will get a flu shot every year as long as Obamacare lets me.
The Flumist nasal vaccine is made with a live virus. Personally, I question the wisdom of putting live virus up people's noses...