I've seen 1 bad reaction to a vaccine in 17.5 years of service. It was the Japanese encephalitis vaccine, a disease which is spread by mosquitos, and the shot was administered to everyone prior to our deployment to Japan. Immediate Anaphylactic shock resulted. The Marine lived but didn't deploy with us. He was still awaiting discharge 8 months later when we returned from deployment. Long-term lasting effects were a heart murmur, I'm not sure if anything else developed after he left the service. It was sad to see, but adverse reactions to vaccines aren't anything new.