Parents are being encouraged to give their child the MMR vaccine by senior figures in the government who fear a rise in measles deaths across the country.
Letters have been sent to primary care trusts today by the chief medical officer, urging them to offer the MMR vaccine to every child up to the age of 18.
Concerns have been raised in the past that the vaccine for measles, mumps and rubella could be linked to autism.
But these have since been disputed and Professor David Salisbury, director of immunisation at the Department of Health, said all children need to be vaccinated.
The number of cases of measles in England is rising following a decade of relatively low vaccine uptake.
It is estimated that around three million children aged 18 months to 18 years have missed either their first or second MMR vaccination.
Scientific advice from both the Department of Health and the Health Protection Agency suggests that levels of MMR immunisation need to be increased as a matter of urgency.
The previous success of the MMR vaccination programme reduced the number of measles cases to very low levels for a number of years.
Between 1992 and 2006 there were no deaths from acute measles in England. However there was one death in 2006 and another in 2008.
"Parents who have not had their children vaccinated with the MMR vaccine should do so now. The evidence on MMR is absolutely clear - there is no link between the vaccine and autism," said Professor Salisbury.
"The MMR vaccine coverage is not high enough to remove the threat of recurrence of measles outbreaks. Measles is serious and in some cases it can be fatal. Delaying immunisation puts children at risk."
Extra funding and vaccines are to be made available by the Department of Health to help trusts vaccinate more children.