I know. Every time I’ve had the flu shot, I got sicker than a dog. Most years I ignore the hype and move on with life. The sickest I’ve been flu-wise was when I have had the flu vaccine. My wife was forced to get it this year by her employer (that or wear a mask until May). She didn’t get sick until about a week later - same for a few of her co-workers. She missed 3 days of work because of it.
I got the flu last year and was given Tamiflu - I felt fine in 3 days, overall it was pretty minor. I missed one day of work.
The best course of action is to eat a well balanced diet, get plenty of quality sleep, and do everything you can to eliminate stress.
Also, be compulsive about washing your hands and limit drugs and alcohol .
These common sense procedures will do far more to keep you healthy than injecting foreign drug cocktails into your body.
Most vaccinations for the flu take up to two weeks to be effective. As reported above, they missed with their guess on the dominant strain this year, so even if she'd had it in time, she may very well have gotten sick anyway. However, the fact that she became ill within a week of getting the shot means that she was exposed before the vaccination could take effect.
Someone lied to your wife.........