I'm sorry that your nephew was injured, but such severe reactions only happen in about 1 in 140,000 doses of the DPT vaccine, or 0.0007%. The fact that he was so supremely unfortunate as to have such a severe reaction is a very sad thing, but the odds of such a reaction are so minuscule and the benefits of using the vaccine so great that you can hardly say that his sad case is an argument against using vaccines.
But to that family whose child was the 1 in 140,000, it's 1 in 1 for them...