Nothing, he is telling you he is an idiot and proving it at the same time.

Unbelievable and ignorant

Was he eating a hot dog at the time? Cause no one knows what's in those things

Wrong question. It should be "What's right with that statement?" to which the answer is "Absolutely nothing at all.".

1. It is very unlikely they know what is in any of the food and drink they take either. 2. It is probably easier to find out what is in the vaccine, than in you food and drink. (Tiny amount of research needed.) 3.The main active part of the vaccine is, obviously, based on small parts of the virus. So this is arguing that a small part could be more harmful than the whole thing. Which is possible, but highly unlikely. A bit like troops running from the battlefield saying. "They have taken their guns apart and are throwing the bits at us. Its just too dangerous."

I could go on, but will that do for a start.