Australian Institute of Health and Welfare (2021) Infectious diseases, AIHW, Australian Government, accessed 03 February 2023.
Australian Institute of Health and Welfare. (2021). Infectious diseases. Retrieved from https://www.aihw.gov.au/reports/children-youth/infectious-diseases
Infectious diseases. Australian Institute of Health and Welfare, 25 June 2021, https://www.aihw.gov.au/reports/children-youth/infectious-diseases
Australian Institute of Health and Welfare. Infectious diseases [Internet]. Canberra: Australian Institute of Health and Welfare, 2021 [cited 2023 Feb. 3]. Available from: https://www.aihw.gov.au/reports/children-youth/infectious-diseases
Australian Institute of Health and Welfare (AIHW) 2021, Infectious diseases, viewed 3 February 2023, https://www.aihw.gov.au/reports/children-youth/infectious-diseases
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Infectious (also known as communicable) diseases are illnesses or diseases caused by infectious organisms or their toxic products. These diseases pass to humans, directly or indirectly, through contact with other humans, animals, or other environments where the organisms are found. They can be caused by bacteria, viruses, parasites of fungi, or their toxic products (AIHW 2020a).
Vaccination is one of the key public health measures that has been greatly successful in reducing infections from serious diseases and in decreasing related disability and death.
Infection with a communicable disease is something most people will experience in their lifetime; these diseases are mostly mild and short lived. Medical assistance, including testing, is not needed or sought in many cases, and therefore the prevalence of these diseases is difficult to determine.
Some diseases must be reported to health authorities, called notifiable diseases, and this allows public health interventions to be introduced to reduce or prevent transmission (AIHW 2020a). Notifiable diseases can vary between states and territories but are generally identified based on the potential severity of harm and/or risk of spread (for national, state and territory lists of notifiable diseases, see Where do I find more information?).
COVID-19 is a disease caused by the coronavirus SARS-CoV-2. By early February 2020, it was declared a notifiable disease in all states and territories in Australia (Widmaier 2020). It was declared a pandemic by the World Health Organization on 11 March 2020 (WHO 2020).
The COVID-19 pandemic has had an impact on almost all aspects of young people’s lives and caused substantial harm worldwide. The measures adopted to control its spread (including social distancing) are likely to have also affected the spread of other infectious diseases. However, the extent to which this occurred is difficult to quantify due to other factors that would have had an impact on notification numbers, such as changes in health care seeking behaviour and laboratory testing priorities (Bright et al. 2020).
Australia’s COVID-19 Vaccine National Rollout Strategy identifies priority populations and phases for the vaccination program (DoH 2021a).
This section focuses on several infectious diseases of particular relevance to young people, including those for which there is a national immunisation program.
National Notifiable Diseases Surveillance System
Data on rates of notifiable diseases come from the National Notifiable Diseases Surveillance System (NNDSS), which coordinates the national surveillance of more than 50 communicable diseases or disease groups. Under the NNDSS, doctors, diagnostic laboratories and hospitals are required by law to notify their state or territory health authority when cases of particular communicable diseases are identified. Every day these data are collated, analysed and published on the internet by the Department of Health (DoH 2020a).
The number of notifications over time can be influenced by increased testing or more sensitive diagnostic tools. Also, not all people with notifiable diseases present for medical care and, for those who do, not all are tested. Thus, notifications represent a portion of all cases in the community (for other causes of variability in notifications, see Technical notes) (AIHW 2018a, 2018b; DoH 2015a).
National HIV surveillance data
National data for human immunodeficiency virus (HIV) come from The Kirby Institute, which conducts research of infectious diseases, including HIV, sexually transmissible infections (STIs) and viral hepatitis. These data are collated, analysed and published in annual surveillance reports and online (see also Where do I find more information?).
Australian Immunisation Register
National data on the rates of immunisation for human papillomavirus (HPV) up to 2017 come from a collection of historical data from the National HPV Vaccination Program Register, which ceased to operate on 31 December 2018 (DoH 2020b). Since then, HPV vaccination data have been recorded in the Australian Immunisation Register (AIR). HPV vaccination coverage rates after 2017 will be included in the 2020 annual immunisation coverage report, which at the time this report was written had not been released (Hull et al. 2020).
The AIR includes vaccines funded under the National Immunisation Program (NIP). A series of vaccinations are given at specific times throughout a person’s life. The NIP provides free vaccines to eligible people (including babies, young children, teenagers and older Australians) to help reduce diseases that can be prevented by vaccination.
The NIP schedule is subject to change. For the most recent schedule, see National Immunisation Program Schedule.
A vaccine preventable disease is an infectious disease that can either be prevented or have its impact reduced by immunisation, generally through a vaccine (AIHW 2019a). Large-scale immunisation programs, such as Australia’s National Immunisation Program Schedule, and other public health measures have resulted in a substantial decrease in the incidence of such diseases.
This section examines selected vaccine preventable diseases: influenza, pertussis, pneumococcal diseases, meningococcal diseases, mumps, measles, rubella and chickenpox. For detailed definitions of each disease, see Where do I find more information?.
In 2020, notifications of vaccine preventable diseases among young people aged 15–24 varied by age, sex and disease (see Technical notes):
Between 2009 and 2020, the notification rate of vaccine preventable diseases among young people aged 15–19 and 20–24 varied greatly by disease type, with similar patterns seen between age groups. However, influenza and pertussis (whooping cough) have consistently had the highest notification rates.
In 2020, nearly all vaccine preventable diseases considered in this section had the lowest notification rates reported in 11 years (except for chickenpox and mumps). As already noted, it is difficult to determine how much of this decrease reflects a real drop in the number of cases occurring, and how much relates to changes in health care seeking and in testing associated with the COVID-19 pandemic.
The rate has fluctuated over time, with the highest rate in the last 10 years in 2019, followed by the lowest in 2020 for both young people aged 15–19 (1,213 and 57 per 100,000, respectively) and those aged 20–24 (1,012 and 59 per 100,000, respectively) (Figure 1).
Note: All NNDSS data were extracted January 2021, see Technical notes.
Source: DoH 2020a.
The rate decreased between 2009 and 2013 for both age groups, and then peaked in 2015–2016, with:
Chickenpox: outbreaks still consistently occur. The notification rates generally increased between 2009 and 2019 for 15–19 year olds (from 8 to 18 per 100,000, respectively) and for 20–24 year olds (7 to 17 per 100,000, respectively). In 2020, there was a large drop in notification rates for both age groups (to 11 and to 8 per 100,000, respectively)
Mumps: a major outbreak occurred in 2015, with:
Meningococcal disease (invasive), pneumococcal disease (invasive), measles and rubella: the rates have remained consistently low (under 5 per 100,000) for 15–19 year olds and 20–24 year olds (figures 3a and 3b).
In 2018, a new meningococcal vaccine covering 4 sub-types was added to the NIP for infants in response to the severity of the disease and recent increases in notifications and deaths (DoH 2018a; Hunt 2018). The vaccine used before this covered only 1 meningococcal disease sub-type.
In 2019, a dose was added to the NIP for 14–16 year olds to be provided under a school-based program (DoH 2019). An ongoing catch-up program also provided a free dose for those aged 15–19 who missed receiving the vaccine at school through their general practitioner or primary care provider (DoH 2019).
Hepatitis is the inflammation of the liver and has non-viral and viral causes (AIHW 2020a).
Notification rates for hepatitis may underestimate the number of infections due to some people having no symptoms and not seeking testing and some not meeting the ‘newly acquired’ case definition (see Technical Notes) (AIHW 2018c).
In 2020, among young people aged 15–24:
From 2009 to 2020, among young people aged 15–19 and 20–24, the notification rates for newly acquired hepatitis B and C have generally remained the same, with larger variations year to year for hepatitis C:
As noted earlier, it is difficult to determine how much of this decrease reflects a real drop in the number of cases occurring, and how much it relates to changes in health care seeking and in testing associated with the COVID-19 pandemic.
STIs are infections that can be passed from one person to another by sexual contact (AIHW 2020a). Young people are disproportionately represented in the number of notifications in a given year. In 2016, 75% of all chlamydia notifications occurred in young people aged 15–29 (DoH 2018b). However, there are barriers to young people accessing prevention, testing, treatment and support for STIs. These include:
Infections may also be asymptomatic, which can reduce the number of infected people who seek testing and treatment (DoH 2018b). This section examines 3 STIs: chlamydia, gonorrhoea and syphilis. For detailed definitions of each, see Where do I find more information?
In 2020, based on data from the NNDSS, among young people aged 15–24:
From 2009 to 2020, among young people:
As has already been noted, it is difficult to determine how much the changes in notifications in 2020 reflect real changes in the number of cases occurring, and how much they relate to changes in health care seeking and testing associated with the COVID-19 pandemic.
Note: All NNDSS data were extracted January 2021, see Technical Notes .
Source: DoH 2020a.
In 2019, based on data from The Kirby Institute, among young people aged 15–24, there were 91 HIV notifications:
The majority of HIV notifications were reported with the exposure classification of male-to-male sexual contact (66 notifications). Other notifications were reported with their HIV exposure classified as:
Between 2008 and 2019, the rate of notifications among young people aged 15–24 varied, with consistently higher rates for males then females (Figure 6).
Source: The Kirby Institute, unpublished
Between 2008 and 2019, the number of notifications among young people aged 15–24 attributed to:
HPV, a highly contagious virus transmitted through sexual contact, is the cause of most cervical cancers (Brotherton et al. 2019). The HPV vaccination was introduced in mid-2007 for all females aged 12–26 until the end of 2009.
As the age of a student in the first year of high school can vary across Australia, age 15 is used as the routine age to review how many students are fully vaccinated (HPV 3 dose vaccination, see Technical notes ) (DoH 2020c).
There has been insufficient time since HPV vaccinations were introduced for the cervical cancer data to show its effects (AIHW 2019b). High-grade abnormalities can develop from HPV and are associated with future cervical cancer. In a study of a cohort of women born in 1992 or later, the incidence of high-grade abnormalities was found to be lower in HPV-vaccinated women than in unvaccinated women (between 2007 and 2014) (AIHW 2019b).
In 2017, 80% of females and 76% of males turning 15 were fully vaccinated for HPV.
Since 2007, the proportion of females and males who received the vaccinations has increased for females (from 74% in 2007 to 80% in 2017) and for males (from 30% in 2013 to 76% in 2017) (Figure 7).
Note: In 2013, some 15 year olds were eligible for catch-up vaccination as part of the 2013–14 male HPV vaccination catch-up program.
Source: DoH 2020b.
There were 6 deaths among young people aged 15–24 in 2018 that were attributed to the vaccine preventable diseases influenza and pneumococcal disease (AIHW 2020b).
For information on Indigenous young people and infectious diseases, see:
For more information on:
AIHW (Australian Institute of Health and Welfare) 2018a. Australia’s health 2018. Australia’s health series no. 16. Cat. no. AUS 221. Canberra: AIHW. Viewed 15 April 2021.
AIHW 2018b. Vaccine-preventable diseases fact sheets. Cat. no. PHE 236. Canberra: AIHW. Viewed 15 April 2021.
AIHW 2018c. Hepatitis B in Australia fact sheet. Cat. no. PHE 236. Canberra: AIHW. Viewed 15 April 2021.
AIHW 2019a. The burden of vaccine preventable diseases in Australia. Cat. no. PHE 263. Canberra: AIHW. Viewed 15 April 2021.
AIHW 2019b. Analysis of cervical cancer and abnormality outcomes in an era of cervical screening and HPV vaccination in Australia. Cancer series no. 126. Cat. no. CAN 129. Canberra: AIHW. Viewed 15 April 2021.
AIHW 2020a. Australia’s health 2020. Australia’s health series no. 17. Cat. no. AUS 232. Canberra: AIHW. Viewed 15 April 2021.
AIHW 2020b. General Record of Incidence of Mortality (GRIM) data. Canberra: AIHW. Viewed 3 July 2020. Viewed 15 April 2021.
Bright A, Glynn-Robinson A-J, Kane S, Wright R & Saul N 2020. The effect of COVID-19 public health measures on nationally notifiable disease in Australia: preliminary analysis. Communicable Diseases Intelligence 44. Viewed 15 April 2021.
Brotherton J, Budd A & Saville M 2019. Understanding the proportion of cervical cancers attributable to HPV. Medical Journal of Australia 212(2):63–5. Viewed 15 April 2021.
DoH (Department of Health) 2015a. Introduction to the National Notifiable Diseases Surveillance System. Canberra: DoH. Viewed 13 November 2020.
DoH 2015b. Hepatitis B (newly acquired) case definition. Canberra: DoH. Viewed 3 March 2021.
DoH 2015c. Hepatitis C (newly acquired) case definition. Canberra: DoH. Viewed 3 March 2021.
DoH 2018a. Clinical update: National Immunisation Program (NIP) childhood schedule changes from 1 July 2018. Media release by DoH, 25 June 2018. Canberra: DoH. Viewed 15 April 2021.
DoH 2018b. Fourth National Sexually Transmissible Infections Strategy 2018–2022. Canberra: Department of Health. Viewed 15 April 2021.
DoH 2019. Clinical update: adolescent meningococcal ACWY vaccine. Media release by DoH, 18 April 2019. Canberra: DoH. Viewed 15 April 2021.
DoH 2020a. National Notifiable Diseases Surveillance System. Canberra: Department of Health. Viewed 22 April 2020.
DoH 2020b. Historical data from the National HPV Vaccination Program Register. Canberra: Department of Health. Viewed 8 July 2020.
DoH 2020c. National (Australia) HPV 3 dose vaccination coverage for all females turning 15 years of age, 2017. Canberra: Department of Health. Viewed 13 October 2020.
DoH 2021a. Australia's COVID-19 vaccine national roll-out strategy. Canberra: DoH. Viewed 15 April 2021.
DoH 2021b. About the Pfizer/BioNTech COVID-19 vaccine. Canberra: DoH. Viewed 15 April 2021.
Hull B, Hendry A, Dey A, Macartney K & Beard F 2020. Annual Immunisation Coverage Report 2019. Westmead: NCIRS (National Centre for Immunisation Research and Surveillance Australia). Viewed 15 April 2021.
Hunt, the Hon. G 2018. $52 million to deliver free meningococcal vaccine to teenagers. Media release by Minister for Health and Aged Care, 25 September 2018. Canberra. Viewed 15 April 2021.
Morrison, the Hon. S 2021. Press conference—Australian Parliament House—07 Jan 2021—Prime Minister. Transcript. Viewed 13 January 2021.
Orenstein WA & Ahmed R 2017. Simply put: vaccination saves lives. Proceedings of the National Academy of Sciences of the United States of America 114(16):4031–33. Viewed 15 April 2021.
Widmaier C 2020. Coronavirus declared a notifiable disease. Health Legal news, 17 March 2020. Melbourne: Health Legal and Law Compliance. Viewed 12 December 2020.
WHO (World Health Organization) 2016. WHO’s mission and vision in immunization and vaccines (2015–2030). Geneva: WHO.
WHO 2019. Hepatitis. WHO website. Geneva: WHO. Viewed 13 November 2020.
WHO 2020. Opening remarks at the media briefing on COVID-19. Media release by WHO Director-General, 11 March 2020. Geneva: WHO. Viewed 9 December 2020.
For general technical notes relating to this report, see also Methods.
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