MMR vaccine is a three part vaccine, given by injection, which is to protect (immunise) against Measles, Mumps and German Measles (Rubella). Normally it is given to children at 12 to 15 months, with a reinforcing dose (a booster) before school, usually between 3 and 5 years.

The Vaccine

The vaccine is a freeze-dried preparation which contains live virus particles of the three viruses, which have been modified (attenuated) to stop them from producing the full effects of the disease.

The vaccine is given, by injection, into the thigh or upper arm. It has been found that a booster, before school, makes it likely that more people will be properly protected.

The idea is to fool the body's defence system into thinking it is under attack by the viruses, and to produce defence mechanisms (antibodies) which will fight off the conditions if they are encountered in the future. There is no risk of someone who has been vaccinated infecting other people with the viruses.

Usually the vaccine is for children, but it can be given to non-immune adults. It is suggested that people in long term institutional care, who are not immune, should have the vaccine. It is also recommended that students starting at college or university, who have not received the vaccine previously, should be offered it.

Reasons for having the inoculation

The most serious of these, as far as how ill the child gets, is Measles, but all of them can have serious and even fatal complications. In the case of German Measles the major worry is that of risk to the unborn baby if caught by a woman during early pregnancy. Mumps too can have serious affects, and affect male fertility, when caught after puberty.

These conditions are still common on a world-wide basis. In countries like the UK, where the take-up rate of immunisations is high, the actual occurrence of the conditions becomes rare. It is not, however, possible to stop immunisation, because of the high level of the conditions elsewhere in the world, and the volume of international travel.

It is true that the amount that a disease occurs (the incidence) will reduce once a certain percentage of the population has been inoculated. This is called "herd immunity". It is possible for some individuals to depend on this and avoid having the vaccine themselves. This is, however, selfish and if everybody had that attitude, the diseases would remain widespread.