I have it every year too. Not usually any side effects but this year felt pretty rough for a couple of days. Of course I could have just happened to pick up a cold at the same time. Either way still well worth it to avoid a proper dose.
I’ve had one for the last few years because I’ve been training for some big events and didn’t want flu to wreck my plans. This year’s strain is meant to be pretty nasty, so I’m gonna try and get one tomorrow. My grandfather as a healthy 60 yr old nearly died many years ago from flu, ended up in ICU and the after-effect dramatically shortened his life.