Most endo's believe in tripple dosses either at 100 or 101F fever.  We choose to double at 100 and tripple at 101.  I agree with Miss Preston that with such a small baby, you cannot be too aggressive.  I have seen my son (will be two on November 10th) go into adrenal crisis too fast to fool around with it.  Even if the fever is caused by a vacine, it is still a sign the child's body saying it is stressed and I am pretty sure it should not be treated differently.