Uptake rates in Leeds are about 80 per cent, with one in five children not having the full combined measles, mumps and rubella vaccination by their second birthday.

Health bosses are warning that means some children could be vulnerable to serious illnesses.

NHS Leeds head of health protection Dr Simon Balmer said: "Nationally, there has been a drop in the number of children being immunised, which has caused an increase in the number of measles, mumps and rubella cases.

"It is really important that children have the MMR vaccine so we can stop the spread of these infections and protect them from future health problems."

Some parents rejected the combined vaccine several years ago after a 1998 study linked it to autism and bowel disease. But more research since then has found no evidence of this.

However cases of measles have been increasing, thought to be because of the lower uptake of the MMR jab.

Nationally, more than 1,000 cases have been confirmed in the UK during 2008, already higher than the 990 recorded in the whole of 2007.
In Leeds, there have been 24 cases of measles in 2008.

Dr Balmer added: "Although the numbers are still small compared to cases recorded prior to the introduction of the MMR vaccination, we're always worried about measles because very rarely it can kill.

Infectious

"The MMR vaccine is proven to be safe and effective. The lower uptake of the vaccine over the last 10 to 15 years has meant that now we are seeing more cases of measles nationally and the risk of a child contracting measles, mumps or rubella is higher than it used to be."

Measles is highly infectious and can lead to pneumonia, lung infections and in rare cases inflammation of the brain.

Mumps and rubella also cause unpleasant symptoms and all three illnesses can lead to permanent deafness or partial hearing loss.
If contracted during pregnancy, rubella can cause birth defects in unborn babies.

Two doses of the MMR vaccine are needed for it to be effective and a drive is underway in Leeds to boost uptake levels.

GPs are targeting patients who have not been immunised and health visiting teams are taking the vaccine to specific areas of the city where take-up is lower.

Staff in children's centres are also being trained to provide information on MMR.