These parents in New Zealand chose to go public with their son's story because they felt there is a lot of misinformation about vaccines on the internet:
Auckland parents Ian and Linda Williams thought they had made an informed choice not to vaccinate their children, but after their son ended up in intensive care with a tetanus infection they realised they had made a terrible mistake.
"The mistake that we made was that we underestimated the diseases and we totally over-estimated the adverse reactions", says father Ian Williams, who is speaking publicly of his family's ordeal in an effort to warn other parents about the dangers of not immunising their children.
You can read the rest of the story at this link: http://www.abc.net.au/local/stories/2013/06/06/3776327.htm 
They have since vaccinated all of their children. Any thoughts on their story?