I would say that your friend and his wife are experiencing this because their body is reacting to the vaccine and building immunity to it. A strong reaction means their body is doing what it’s supposed to and fighting off what it thinks is the virus.

Pretend this wasn’t because of a vaccine. Say your friend and his wife had gotten a cold or stomach virus. They are experiencing the same side effects. This would be deemed good because the body is ridding itself of the bad stuff in any way it can.

The fever causes the body to sweat out of the invader. Throwing vomiting is expelling it through the mouth. The body is doing whatever it needs l, whichever way to get rid of it. It shows that their body is working and understands the job it needs to do, to get them back on track.

I’m not medical personnel. This is just my knowledge and experience with vaccines and sicknesses. Take it for what it’s worth.