With the flu, basically you're bed-bound.

Someone gets vaccinated and a short time later they get a different virus and they tend to associate that illness with their prior vaccination. They confuse the other viral infection with the flu.

The other trick is not to go to bed until you're tired. It's counterproductive to lie in bed awake.

For my mother's and grandmother's generation, their teeth were in a jar by the bed. They didn't have any teeth.

I jumped out of bed and headed for the hospital.

When it gets bad enough, where it is affecting academic work - crying, can't get out of bed, a feeling of hopelessness - that is when people need to get help.