The number of measles cases is rising and health experts are worried that this could be the start of a new epidemic.
So far this year there have been 449 confirmed cases of measles in England and Wales. Many of these have been in Surrey, Sussex and Doncaster. This represents a significant increase as there were just 77 cases for the whole of 2005.
Since the MMR scare in 1998 the number of children being immunised has fallen and many health workers think that this is allowing measles to become established again.
In Surrey, parents have received letters from the Health Protection Agency recommending that in some cases a first dose of MMR vaccine should be given as early as nine months - current guidelines say after the child's first birthday. The second dose, or booster, is also being brought forward to anytime after 18 months - at the moment it's usually given just before a child goes to school.
Jenni Murray hears from worried parents and speaks to Dr Peter English, Consultant at Surrey and Sussex Health Protection Agency and Helen Bedford, Senior Lecturer in Children's Health at the Institute of Child Health.
