What is immunisation?

Immunisation is the use of a vaccine to protect against a disease. Vaccination is simple, safe and effective. The risks of having these diseases are far greater than the risk of any minor side effects from immunisation.

How do vaccines work?

A vaccine contains small parts of the viruses or bacteria that cause the disease; however they have been either killed or weakened so that they will not cause illness and are safe to use.

When you are given the vaccine, your body responds by making substances called antibodies. These then stay in the body and protect against future infections.

In addition to the active ingredients, vaccines may contain small amounts of additives. These additives may protect the vaccine from contamination, for example, or help the body to respond to the vaccine. The level of additives used in vaccines is very low and will not cause any serious health problems.

When are vaccinations given?

Most vaccines are given to babies during the first year of life, through the Childhood Immunisation Programme, with further boosters given during childhood. They are given at such a young age in order to give children protection against disease as early as possible.

Some other vaccines may be given if necessary to adults. For instance, the influenza and pneumococcal vaccines are routinely recommended for all adults over 65 years of age. Travel vaccinations may be required when travelling to certain countries.

Why should I have my child immunised?

Medical opinion is almost unanimous that children should be vaccinated against certain contagious diseases at an early age. Diseases such as rubella or measles can be fatal, and were a major cause of infant death in times before a national vaccination scheme was introduced.

Public vaccination has led to the eradication of a number of these diseases in Ireland such as smallpox, and could eliminate other fatal diseases in the future. Because vaccines have been so successful, you can now expect your immunised child to avoid getting diseases such as polio, whooping cough and measles. Today, in parts of the world without comprehensive vaccination, children are still dying from these illnesses in significant numbers.

In the absence of immunisation, these kind of diseases could become commonplace again in Ireland, causing significant amounts of serious illness and potential deaths. For instance, a decline in uptake of the MMR vaccine in recent years due to a loss of confidence in the vaccine among parents, led to rise of measles cases in 2000 – which included the death of 3 children.

Having your child immunised gives extra protection against illnesses that can kill.

Which childhood diseases can be prevented by immunisation?

  • Polio
  • Diphtheria (respiratory disease spread by coughing and sneezing)
  • Tetanus (neurological disease also known as lockjaw)
  • Pertussis (highly contagious respiratory disease also known as whooping cough)
  • Measles
  • Mumps
  • Rubella (also known as German measles)
  • Haemophilus influenzae type b (causes meningitis, pneumonia, sepsis, arthritis and skin and throat infections)
  • Varicella (also known as chickenpox)
  • Hepatitis B (can destroy the liver)
  • Meningitis C
  • Streptococcus pneumoniae (vaccination only recommended for certain people at risk)

How likely is it my child will be exposed to these diseases?

While some of these diseases are now rare in Ireland, others are still fairly common. In addition, they may be common elsewhere in the world – for instance, diphtheria is still common in Asia despite it being rare in Ireland. With increased travel to different countries nowadays, diseases that are now rare in Ireland could be brought back into the country and could become common again. If enough people aren’t immunised, epidemics would follow.

Are vaccines safe?

All medicines can cause side effects, but with vaccines, these are usually mild and temporary – like a sore arm or leg, or a slight fever. Serious side effects to vaccines are extremely rare. Very rarely, children can have allergic reactions straight after immunisation. If the child is treated quickly, he or she will recover fully. People giving immunisations are trained to deal with allergic reactions.

Before any vaccine can be used it has to go through many tests. All the recommended vaccines used to protect children in Ireland are licensed by the Irish Medicines Board or the European Medicines Evaluation Agency. They are only allowed to be used after they have been shown to be both safe and effective. Each vaccine is continually checked after it has been introduced and action is taken if it is needed.

How effective are vaccines?

Vaccines are very effective, but not every child may respond to them. Most childhood immunisations protect around 90-99% of the children who get them. A child who does not respond to a vaccine depends on the immunity of those around them for protection, so this is another reason why it is important for all children to be immunised.

Are there any reasons why my child should not be immunised?

There are very few reasons why a child should not be immunised, but you should let your doctor know if your child has:

  • A brain disorder — usually the paediatrician will specifically say whether or not the whooping cough vaccine can be given
  • A high fever
  • Had a bad reaction to another immunisation
  • Had, or is having, treatment for cancer
  • Has a bleeding disorder
  • Has had a severe reaction after eating eggs
  • Has had convulsions (fits) in the past — with the right advice, children who have had fits in the past can be immunised
  • You should also let your doctor know if your child or any other close family member:
  • Has any illness that affects the immune system, for example, HIV or AIDS
  • Is taking any medicine that affects the immune system — for example, immunosuppressants (given after organ transplant or for malignant disease) or high-dose steroids, for example for treatment of asthma
  • Allergic to any antibiotic
  • Has recently had immunoglobulin or blood transfusion or another vaccine.

Find out more about the Childhood Immunisation Programme runs a Child Vaccination Tracker Service that will alert you to the vaccinations that your children need as they grow. Access the Child Vaccination Tracker here:

Reviewed: September 28, 2006