Vaccinations don't always give life-long protection. Some vaccines need to be presented to a child's immune system on multiple occasions in order for an adequate immune response to occur - that's why a 'course' of vaccines might be given (e.g. the combined measles, mumps and rubella vaccine is given in two doses; each dose given at a different age).

Even after a full course is completed, some vaccinations, such as whooping cough vaccine, give protection for a limited time.  Subsequent booster doses are recommended to maintain immunity. Other vaccines may provide immunity for longer periods, and therefore, a booster may not be needed until adulthood (e.g. tetanus vaccines).

So it's important for your child to receive all the recommended doses - talk to your doctor or nurse for advice on staying current with your child's vaccinations.

Like all medicines, vaccines are not 100% effective.  A small proportion of people - including babies and children - may still get the disease even though they are vaccinated. If people are not vaccinated - they are more likely to catch the disease and potentially experience complications. Although the unvaccinated are more likely to get a disease, the chances of being exposed are reduced when most people in a community are vaccinated.

Some side effects are a sore arm, fever, and pain, redness and swelling at the injection site. A range of other and more serious side effects may be experienced by individuals and may vary depending on the vaccine given.  If your child experiences any side-effects, regardless of how minor the symptoms are, make sure you report them to your doctor.

It is worth remembering that the diseases prevented by vaccination can be very severe.  If you have any concerns about the side-effects of vaccines, speak to your doctor before your child is vaccinated.

If enough people in the community are not vaccinated, significant illness (and even death) can occur when a serious disease spreads- despite excellent hospital care and living standards. For example,  before the introduction of the Haemophilus influenzae type b (Hib) vaccine in Australia in 1993, there was a greater number of Hib cases reported in children under the age of 5 -502 cases in 1992, compared to approximately 15 cases in 2005. Also, some of the diseases Australian children are vaccinated against are still common in other areas of the world, and therefore travelling to these areas can potentially pose a risk to an unvaccinated child/individual.

There are medical reasons for delaying vaccination, such as a child with a high temperature (over 38.5ºC) or someone who has a weakened immune system (e.g. receiving chemotherapy).  Other medical conditions may also need to be considered.  Speak to your doctor about your child's circumstances before postponing vaccination. You can also complete a pre-vaccination checklist to help your doctor decide about immunising your child.