My #1 reason for not giving the DTaP: it is the vax associated with the most serious reactions, and the most long term consequences. Not just mild fever and irritability (although that is a possibility), but irreversible brain damage. If there is one vax NOT to get, IMO, it's the DTaP. http://www.washingtonpost.com/wp-srv...hots/shot1.htm
This article is about the DPT, and the formula has since changed to be DTaP. But the new vaccine is not much safer.