I have the flu jab every year due to mild asthma and have never had a reaction to it or got the flu after or since. Makes me laugh how some people when they get a cold say they have the flu. I've had proper flu once before I got the regular jabs and I thought I was literally dying, so much so that my Mrs called out the emergency doctor and it put me in bed for two weeks.
Now we (male folk) know about the man-flu

and that can be a bugger in its self and can upset daily activities for a couple of days but it certainly isn't equivalent to full blown proper flu.