What are, the challenges associated vaccination programs?

Good question: Any vaccination implies a needle. This results in an ultra low voltage electric current through the body. If body metabolism is only marginal, this "pin prick" may become a stress factor, apart from the action of the vaccine itself. That is why most kids do not have a problem. If there is a metabolic risk, in uncommon cases, it can cause problems. That is why diet is so vital.

Vaccine phobia,: Fueled by the media since the first spurious study on MMR & autism, is the #1 challenge. See jennymccarthybodycount.Org. The cost to pediatricians & family medicine doctors often means they lose money when they provide vaccines in their offices. No matter the challenges, timely vaccine administration is vital since " herd immunity" no longer protects infants-adults from outbreaks.

IgnoranceAndReligion: Challenges are people for some reason believing that Vaccines are harmful and refuse to vaccinate on basis of fear of Autism even though that has been proved not true.Religious belief and simple ignorance influenced by AntiVaxGroups with fear propogatd by false stories and beliefs