Immunisation

Why do we immunise?

A paediatrician talks about why we immunise babies and young children.

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There are three reasons why we immunise children. First, immunisation prevents children from becoming ill with unpleasant and serious infectious diseases, which have a risk of complications and long-term side effects. Until these diseases are eradicated, each child that is not immunised is at risk of these complications if they catch the actual infectious disease itself, for instance in the case of children who actually catch measles itself complications such as ear infections, pneumonia and in rare cases, measles encephalitis (a rare brain disease which can occur in one in 5000 cases of actual measles infections) can occur.

Second, we immunise to try and help protect all children in the population. The more people who are immunised, the less of the infectious disease there is around so the less chance there is of anyone catching it. When levels of immunisation against an infectious disease is really, really high - then something happens called 'herd immunity' where the risk of the disease occurring is so low that even those who cannot be vaccinated are unlikely to be affected. When this happens it means that even children who have leukaemia or other forms of lowered resistance to infections who cannot be given live vaccines such as measles, mumps and rubella vaccine and the polio vaccine - and also babies under the age of one who are too young to have the measles, mumps and rubella vaccine will also not be exposed to the disease.

Third, we immunise to try and wipe out as many infectious diseases as we can everywhere in the world. Although improvements in living standards and cleaner water have been key factors in the decline of infectious diseases in the United Kingdom and elsewhere in the world, it is quite clear that the immunisation programmes have made a huge and significant impact in getting rid of infectious diseases as well. In the ten years before the measles vaccine was introduced in to the United Kingdom in 1968, there were around 380,000 cases a year of measles and 850 deaths (Bedford, Elliman, 2001). Measles, mumps and rubella vaccine was introduced in the United Kingdom in 1988. In the ten years since then - between 1989 and 1998, there were only four deaths associated with acute measles and 19 deaths resulting from the measles complications.

In 2008, there were outbreaks of measles in London, resulting in a total of 664 cases.

There are three reasons why we immunise children. First, immunisation prevents children from becoming ill with unpleasant and serious infectious diseases, which have a risk of complications and long-term side effects. Until these diseases are eradicated, every child that is not immunised is at risk of complications if they catch the actual infectious disease itself. Complications such as ear infections, pneumonia and in rare cases, measles encephalitis (a rare brain disease which happens in one in 1,000 cases of infected children) can occur - Oxford University - Oxford Vaccine Group March 2013.

Second, we immunise to try and help protect all children in the population. The more people who are immunised, the less of the infectious disease there is around so the less chance there is of anyone catching it. When levels of immunisation against an infectious disease are really, really high - then something happens called 'herd immunity' where the risk of the disease occurring is so low that even those who cannot be immunised are unlikely to be affected. When this happens it means that even children who have leukaemia or other forms of lowered resistance to infections who cannot be given live vaccines such as measles, mumps and rubella vaccine and the polio vaccine - and also babies under the age of one who are too young to have the measles, mumps and rubella vaccine will also not be exposed to the disease. This is important as measles can be fatal for these children. The proportion of immunised children (vaccine coverage) required to produce herd immunity varies from disease to disease, but is estimated to be about 95% for measles.

Third, we immunise to try and wipe out as many infectious diseases as we can everywhere in the world. Although improvements in living standards and cleaner water have been key factors in the decline of infectious diseases in the United Kingdom and elsewhere in the world, it is quite clear that the immunisation programmes have made a significant impact in getting rid of infectious diseases as well. In the ten years before the measles vaccine was introduced in to the United Kingdom, there were around 380,000 cases a year of measles and 850 deaths (Bedford, Elliman, 2001). Measles, mumps and rubella vaccine was introduced in the United Kingdom in 1988. In the ten years since then - between 1989 and 1998, there were four deaths associated with acute measles and 19 deaths resulting from complications from measles.

The recent increase in the numbers of cases of mumps and measles in the United Kingdom is a direct result of children not being immunised following unfounded and unnecessary scares about the measles, mumps and rubella vaccine. In 2012 there were 2016 laboratory-confirmed cases of the measles in England and Wales- compared with just 374 cases in 2010 (NHS Choices - 2013). This has since dropped to 130 cases in 2014 (Public Health England August 2015).

Last reviewed October 2015.
Last updated October 2015.