Vaccines work by training the immune system to recognise and fight off invading organisms. Although often used interchangeably, the terms vaccination and immunisation are not the same; vaccination is the process of receiving a vaccine, while immunisation is the process of receiving a vaccine and becoming immune to a disease as a result of being vaccinated.

In Australia, routine immunisation begins at birth, and includes vaccines against 17 diseases, including measles, mumps, and whooping cough.

A large proportion of the community must be fully immunised for the preventive health measure to have the greatest benefit. The aspirational national immunisation target for childhood immunisation at the age of 5 is 95%. This rate has been achieved for Aboriginal and Torres Strait Islander children, but not for all children.

When are children immunised?

The Australian Government provides funded vaccines against 17 diseases to eligible people through the National Immunisation Program (NIP). Australian children are expected to have received specific vaccinations by the ages of 1, 2 and 5. The immunisation rates at all 3 ages are above 90%. The rate for Indigenous children is slightly lower than the rate for all children at the ages of 1 and 2, but by the time Indigenous children are 5 years old they are more likely than all children to be fully immunised.

The NIP also provides funded vaccines for adolescents, older people and others at high risk. For example, the influenza vaccine is available to pregnant women, Indigenous Australians in most age groups, people aged 65 and over, and people who are medically at risk. A national human papillomavirus (HPV) vaccination program is also available for Australian girls and boys, aged up to 19. Vaccinations are routinely given in school-based programs when children are aged 12–13.

Australia has relatively high levels of immunisation, however, vaccination rates vary by where a child lives. For example, rates for 5 year olds range from 90.6% in the North Coast of New South Wales to 96.0% in Western New South Wales.