I have a flu jab every year which my employer provides. It's not a live vaccine, so won't give you flu. I've never had any symptoms whatsoever from this vaccination, in fact the only symptoms I've ever had from any vaccination was an achey arm for a few hours. This was several years ago when I was working on live medical vaccine production and had to have cholera/typhoid injections every six months to protect me. The only problem with the vaccination is that it wioll only provide cover for the specific strain, so if a different strain wanders along.......
Genuine flu is horrible and can be fatal for vulnerable patients.