My entire family (adult kids, grandkids, my Dad, hubby and myself) all had the flu over the Millennium (Dec-Jan 1999-2000) My anniversary was Dec. 29, the day I started getting sick, so had to skip going out that night, and I slept through the New Year's festivities, and most of the day New Year's Day. It lasted 10 days almost exactly. We had friends bringing food, for those of us who could eat. My son in law had pneumonia. It was the worst flu I've ever had. The next year we got flu shots.
We haven't gotten them again though. I have been more dilligent about building up my immune system, and am in very good health now.
I took Mom (age 90) for her flu shot two weeks ago, and she got sick for three days after. The instruction sheet they gave me said it might happen. Her arm hurt very badly and she had nausea and couldn't eat and sleep well. She's fine now though.
It's a personal decision. I am into alternatives, not because of having been raised a dub, but because of my father being a Naturopath.