Throughout our lives, we’re exposed to many different germs which are potentially harmful to us. Some of these, like colds, are minor and our bodies can easily fight off. Others can be more harmful and immunisation is a way to minimise the likelihood of contracting these preventable diseases.

Generally, immunisations are given in the form of an injection, which can be frightening for parents and children. If you’re concerned about immunisations, check out our information on preparing your child for immunisations.

How does immunisation work?

Put simply, immunisation gets the body to respond to a weakened version of a disease so that later the body is able to fight off the real thing. You can read more about which immunisations are given to children in New Zealand in our page on the New Zealand Immunisation Schedule.

The body uses specialised immune system cells and generates small molecules called “antibodies” to fight infections,. The first time we come across a germ, it takes a while for the immune response to get going, so we get sick. The next time we come across the same germ, the body will be able to remember the infection and mount a much faster response.

Immunisation works in a similar way. Instead of the dangerous germ, vaccines are made of components of the germ that can’t cause disease or from weakened versions of viruses. The vaccine doesn’t cause the disease, but teaches the immune system to recognise the invaders in the future.

Types of immunisation

There are two broad classes of immunisation – active or passive.

Active immunisation involves the body generating its own specialised cells and antibodies to fight off the infection. This approach takes longer because it needs to generate the right response, but it teaches the immune system to remember how to respond to the germ if it is encountered in the future. This type of immunity lasts a long time.

Passive immunisation involves passing ready-made antibodies directly into the person being immunised, allowing for immediate protection. Antibodies are passed from mothers to children across the placenta or through breast milk, but antibodies that have been made and purified in a laboratory can also be directly injected. Mothers pass antibodies against some diseases that they have been exposed to on to their children, protecting their babies for a short time after birth. This type of immunisation is temporary and doesn’t protect against all diseases.

Why should I immunise my child?

Some of the diseases that children are immunised against can be very harmful, particularly for babies and small children such as meningococcal disease (blood poisoning and Meningitis). Others, such as measles are highly contagious and usually fairly mild, but pose a risk of serious complications (around 15% of measles cases are hospitalised).  Immunising your child means that they are far less likely to contract the disease and if they do, the effects are likely to be much less significant.

How well does immunisation work?

Immunisation works very well to prevent a wide range of serious diseases. Sometimes, immunisation isn’t completely successful .. In cases like this, children might get the disease, but usually don’t get as sick as they would if they weren’t immunised. While vaccines can’t provide 100% protection to all people, the more people that are immunised, the less the diseases will spread through the population.

Useful Websites

The Immunisation Advisory Centre – this is part of The University of Auckland and has experts available to give advice on immunisation.

The Ministry of Health’s website –  Contains a good introduction to immunisation and latest updates about disease outbreaks as well as immunisations.

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Kate Anderson is a trained Well-Child Nurse with two little people of her own. She also runs Stroll Smart NZ and loves getting out and about with her buggy.

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