This is given when your child is between 12 and 15 months and then agains when your child is three to five years. The MMR vaccine protects your child against measles, mumps and rubella (German measles).

What is Measles?
The measles virus is very infectious. It causes a high fever and a rash. About one in 15 children who gets measles is at risk of complications which may include chest infections, fits and brain damage. In severe cases measles can kill.

What is Mumps?
The mumps virus causes swollen glands in the face. Before immunisation was introduced, mumps was the commonest cause of viral meningitis in children under 15. It can also cause deafness and swelling of the testicles in boys and ovaries in girls.

What is Rubella?
Rubella, German measles, is usually very mild and isn't likely to cause your child any problems. However, if a pregnant woman catches it in her early pregnancy, it can harm the unborn baby.

Do Children Really need Protection Against These Illnesses?
In some children the illness may pass almost unnoticed, but others can be very ill. The most dangerous thing about these illnesses is that they can cause complications.

Before the vaccine was introduced, about 90 children a year in the UK died from measles. Because of immunisation, children no longer die of measles.

Why are Two Doses of MMR Given?
Your child will receive two doses because measles, mumps and rubella vaccines don't always work well enough on the first go. The second MMR immunisation makes sure that your child gets the best protection against these three diseases. This also gives a second chance for those children who missed out the first time around. So, you can be sure your child is well protected before he or she starts school. Giving a second dose of MMR is recent improvement to children's immunisation in the UK. Two doses are already used in this way in many countries including the USA and Canada.

Occasionally, children do have a bad reaction to MMR vaccine. About one child in 1000 will have a fit. A child who actually has measles is ten times more likely to have a fit as a result of the illness. Although encephalitis (inflammation of the brain) has been reported very rarely after immunisation, the risk of children developing encephalitis after the measles immunisation is no higher than the risk of children developing encephalitis without the vaccine. But the risk of a child developing encephalitis after having measles is about one in 5000. And a third of these children will be left with permanent brain damage. A study of British children shows that ten years after the measles immunisation, children had no more illnesses than children who had not been immunised - and actually had fewer because they were protected against measles an did not suffer its complications.

Your child may get a rash of small bruise-like spots after the MMR, but this is very rare. This rash is linked with the rubella part of the immunisation. If you see spots like this, show them to your doctor.

Side-effects from the second MMR vaccine are even rarer than after the first. Those that do happen are most likely in children who did not respond to the first vaccine. These are the children who need the immunisation most. There are no new side-effects of a second MMR vaccine.

What are the Side Effects?
About a week to ten days after the MMR immunisation some children become feverish, develop a measles like rash and go off their food for two or three days. Very rarely, a child will get a mild form of mumps about three weeks after the injection. Your child will not be infectious at this time, so he or she can mix with other people as normal.

Occasionally, children do have a bad reaction to MMR vaccine. About one child in 1000 will have a fit. A child who actually has measles is ten times more likely to have a fit as a result of the illness. Although encephalitis (inflammation of the brain) has been reported very rarely after immunisation, the risk of children developing encephalitis after the measles immunisation is no higher than the risk of children developing encephalitis without the vaccine. But the risk of a child developing encephalitis after having measles is about one in 5000. And a third of these children will be left with permanent brain damage. A study of British children shows that ten years after the measles immunisation, children had no more illnesses than children who had not been immunised - and actually had fewer because they were protected against measles an did not suffer its complications.

Your child may get a rash of small bruise-like spots after the MMR, but this is very rare. This rash is linked with the rubella part of the immunisation. If you see spots like this, show them to your doctor.

Side-effects from the second MMR vaccine are even rarer than after the first. Those that do happen are most likely in children who did not respond to the first vaccine. These are the children who need the immunisation most. There are no new side-effects of a second MMR vaccine.

What About Children Who are Allergic to Eggs?
The MMR vaccine is prepared in egg but it can be given to children who are allergic to eggs. If your child has had a serious reaction to eating eggs, or food containing egg, then talk to your doctor. The usual signs of a serious allergic reaction are a rash that covers the face and body, a swollen mouth and throat, breathing difficulties and shock. In these cases your doctor can make special arrangements for the immunisation to be given safely.

Is there a Link between Autism and MMR?
Autism was well-know long before MMR was ever used in this country. Although autism is recognised more often now than in the past, the increases were going on long before MMR was introduced. Parents often first notice signs of autism in children after their first birthday, and MMR is usually given when children are 12 to 15 months old, so it is possible to see how people might think that there is a link with MMR. But, there is no evidence, other than coincidence, to link MMR with autism.

Is there a Link between Measles, MMR and Crohn's Disease?
It has been suggested that measles viruses, either from the natural disease or the vaccine, might stay in the bowel and cause a bowel disorder called Crohn's disease. Careful independent studies in this country and abroad, using the most sensitive tests, have not found measles viruses in the bowel of people with Crohn's disease. Also, Crohn's disease is no more common in immunised people than in people who have not been immunised. The conclusion of experts from all over the world, including the World Health Organisation, is that the evidence is firmly against any link between measles and MMR vaccines and Crohn's disease.

If you want more information about MMR, your GP or health visitor should have a leaflet, MMR - the facts, and can answer any additional questions you may have.