Err, that's what vaccination does - it exposes the immune system to "bad things" in safe/small quantities so that a response can be mounted when the correspondi

Err, that's what vaccination does - it exposes the immune system to "bad things" in safe/small quantities so that a response can be mounted when the corresponding real threat is presented. Some of the difficulty with SARS/MERS/COVID was that the immune response from a younger, healthy person was able to kill them rather than kill the virus. The optimum would be an immune system that could recognize threats and mount an appropriate response. This is why there's a hunt for common elements of, say, viruses that could be targeted by vaccines - something that is under strong evolutionary pressure to remain constant. Finding such targets would greatly simplify things.