'Vaccine gap' for world's children
16 October 2013 Last updated at 20:53 BST
Despite a huge rise in the take-up of vaccines for preventable diseases, millions of children around the world are missing out on immunisations.
The World Health Organisation has said that improvements in vaccine programmes have seen global child mortality half since 1990, but health campaigners have called for further action.
Fergus Walsh reports.