5. Immunisation
Why is immunisation important?
Immunisation coverage reflects the capacity of the health-care system to provide vaccinations to children.
Immunisation uses the body’s natural defence mechanism―the immune response―to build resistance to specific infections. A large part of the reduction in mortality and morbidity among children over the past century was due to immunisation (Plotkin & Plotkin 2008). Immunisation resulted in the worldwide eradication of smallpox, the widespread elimination of poliomyelitis and can protect children against a multitude of other communicable diseases. Children who do not receive complete and timely immunisations remain at risk of contracting vaccine-preventable diseases, and the short- and long-term health consequences associated with these.
Immunisation also plays a role in protecting individuals who are not immunised, through ‘herd immunity’ (Department of Health 2013a). Generally, immunisation coverage needs to exceed 90% in order to achieve and maintain the level of herd immunity needed to interrupt the spread of the vaccine-preventable diseases (Lister et al. 1999). Australia has an excellent record in childhood immunisation coverage, achieving at or above 90% average coverage for children at 12 months, 24 months and 60 months of age.
In the 2018 Australian Childhood Immunisation Register, 90.5% of children on the Australian Childhood Immunisation Register were fully immunised at 2 years of age (Department of Health 2018). In 2015, more than 1.3% (equivalent to around 30,000 children aged under 7 were not vaccinated because their parents were vaccine objectors (Department of Health 2016). This equates to an increase of more than 30,000 children over the last 10 years. In order to protect children and the community from preventable diseases, the Australian Government has removed ‘conscientious objection’ as an exemption category for child care payments on 1 January 2016. Maintaining and improving these high immunisation rates will continue to be important in the future (Department of Health 2013b; Hull et al. 2016).
Do immunisation rates vary across population groups?
At the national level, in 2016 there were slight differences in immunisation rates between different population groups, with rates varying between around 90% to 92% irrespective of sex, socioeconomic position, or remoteness. National immunisation rates for Indigenous and non-Indigenous children are similar despite coverage for vaccines recommended only for Aboriginal and Torres Strait Islander children remaining substantially lower than that for universal vaccines (DoH 2013c).
Has there been a change over time?
Over the period 2008 to 2014, immunisation rates in Australia at a national level have remained largely stable, between 92 and 93%. However, marginal differences occur between 2008 and 2014 across gender, different socioeconomic position and remoteness areas. There was a slight improvement in immunisation rates for Indigenous children at 2 years of age rising from 91% in 2008 to 93% in 2014.
From quarter ending 31 December 2014, meningococcal C (given at 12 months), and dose 2 measles, mumps, rubella (MMR) and dose 1 varicella (given as MMRV at 18 months) were included in the definition of fully immunised for the 24-27 month cohort. This new definition has been used to produce the 2015 and 2016 fully immunised at 2 years of age rate, and consequently the 2015 data should not be compared to previous years due to a break in the time series (see Notes section for further details).
The immunisation rates for children who were fully immunised at 2 years of age in Australia has increased slightly from 2015, rising by 0.8 percentage points from 90% in 2015 to 90.8% in 2016. Similar patterns were seen among boys and girls, with boys increasing from 90.1% in 2015 to 90.9% in 2016, and girls increasing from 89.9% in 2015 to 90.7% in 2016. For Indigenous children, the immunisation rates increased 2.6 percentage points from 87.1% in 2015 to 89.7% in 2016. For socioeconomic status, there was a slight increase in national immunisation rates (by 0.4 percentage points) in both the lowest and highest socioeconomic status areas. By remoteness, the national immunisation rates also increased in Major cities and Inner regional areas (by 0.7 and 0.8 percentage points, respectively), while Outer regional, remote and very remote areas increased by 2 percentage points, from 90.1% in 2015 to 92.1% in 2016.
Notes
Data from the Australian Childhood Immunisation Register prior to 2015 include children who have received the scheduled doses of vaccines for diphtheria; tetanus and pertussis; poliomyelitis; hepatitis B; Haemophilus influenza type B (Hib); and measles, mumps and rubella. The data exclude other scheduled vaccines for children aged up to 2 years (rotavirus, chicken pox, meningococcal C and pneumococcal conjugate).
The inclusion of these immunisations to the coverage calculation means that for 2015 data, a considerable drop in the 24-27 month coverage rates was observed. The coverage rate has dropped because the criteria to assess fully immunised now includes more vaccines. The more vaccines included in the assessment, the higher the likelihood of reduced coverage rates. This usually resolves over time as the changes become more routine.
Age is calculated as at 30 June.
The data presented for the Total Persons (per cent and number) differ marginally from similar immunisation coverage data published by ACIR due to slight variations in the programs used to calculate the coverage estimates. Any differences observed will not be large enough to affect any interpretation of the data.
It should be noted that data used in this report is for the September quarter (collected over a three month window) in each year; this includes the total number of children. The number of children fully immunised at 24 months is therefore about 4 times the number fully immunised in each September quarter.
References
- Department of Health 2018. Current coverage data tables for all children. Canberra: Department of Health. Viewed 6 August 2018.
- Department of Health 2016. Immunise Australia Program. ACIR current data: national vaccine objection (conscientious objection) data. Canberra: Department of Health. Viewed 7 March 2016.
- Department of Health 2013a. The Australian Immunisation Handbook. 10th edn. Canberra: Department of Health.
- Department of Health 2013b. National Immunisation Strategy for Australia 2013-2018. Canberra: Department of Health
- Hull BP, Dey A, Beard FH, Menzies RI, Brotherton JM & McIntyre PB 2016. Immunisation coverage, 2013. Communicable Diseases Intelligence 2016;40(1):E146–E169.
- Lister S, McIntyre PB, Burgess MA & O’Brien ED. Immunisation coverage in Australian children: a systematic review1990-1998. Communicable Diseases Intelligence 1999;23(6):145-170.
- Plotkin SL & Plotkin SA 2008. A short history of vaccination. In: Plotkin SL, Orenstein W & Offit P(eds). Vaccines. 5th Edition. Elsevier Health Sciences.