Diphtheria

Key facts

  • Diphtheria is a serious disease that can cause breathing difficulties; heart, brain and nerve damage; and, in some cases, death.

  • Due to the vaccination program, diphtheria has been rare in Australia for a long time, but recently a small number of cases have been reported again. 

  • In Australia, all infants and young children are recommended to be vaccinated against diphtheria. To keep this level of protection in adolescence, a booster dose is recommended for all 12- and 13-year-olds.

Last updated on 13 August 2025.

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When to vaccinate against diphtheria

It is recommended that your adolescent receives a booster vaccination against diphtheria at 12–13 years.


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What is diphtheria?

Diphtheria is a serious disease that spreads between people through droplets in the air (especially from coughs and sneezes) or through direct contact.1 The diphtheria germ (bacteria) can cause severe swelling of the throat or neck, blocking the airway and affecting breathing. 

You may not have heard of diphtheria because it is so rare in Australia now, due to high immunisation rates – but before vaccines were available, it was a common cause of death in children.2 

The vaccine is still used in Australia because there is a particular risk from travel to countries where diphtheria remains more common, including in the Western Pacific Region and Southeast Asia. Recently, a small number of cases have been reported again in Australia.2,3

What will happen to my adolescent if they catch diphtheria?

Usual symptoms

  • Diphtheria infection usually begins with a sore throat and fever, and there may be neck swelling and difficulty swallowing. In severe cases, it causes a skin or film (membrane) to grow in a person’s throat, making it hard for them to breathe.
  • It can also cause skin sores that don’t heal, get deeper over time (ulcers) and leave a scar.
     

Less common symptoms

  • People with diphtheria can become paralysed if the disease affects their nerves.
  • Diphtheria can cause heart disease and heart failure.
  • Up to 16% of people who get diphtheria infection die.4

If your adolescent is tested and diagnosed with diphtheria, your local state or territory Public Health Unit (PHU) will be notified. The PHU can provide advice on any public health measures your household should follow. These can include staying home from school or work or wearing a mask.

What vaccine will protect my adolescent against diphtheria?

In Australia, adolescents are recommended to receive a combined vaccine (dTpa) that strengthens immunity to diphtheria as well as tetanus and whooping cough (pertussis).

This vaccine is also recommended for infants, small children and pregnant adults.

When should my adolescent be vaccinated?

To extend the protective level of diphtheria immunity from childhood, adolescents are recommended to get a booster dose of a vaccine that protects against diphtheria at 12–13 years of age (year 7 or equivalent). This booster extends the protective level of diphtheria immunity into their adult years.

This dose is usually given via free school-based immunisation programs. The age of vaccination can differ across states and territories. 

Your adolescent can also receive this routine vaccine through a clinic visit with other immunisation providers.

Even if your adolescent is mildly unwell on the day of their appointment (this means no fever and a temperature under 38.5°C), they can still receive the vaccine.

How does the diphtheria vaccine work?

The vaccine works by ‘training’ your adolescent’s immune system to recognise and get rid of the diphtheria bacteria and their toxin. The vaccine contains antigens, which are tiny, harmless fragments of the diphtheria toxin. 

When your adolescent’s immune system detects the antigens in the vaccine, it produces antibodies. These antibodies are like soldiers that recognise and remember the diphtheria toxin. If your adolescent is ever exposed to the real diphtheria bacteria and their toxin, their immune system will recognise it quickly and fight it off using the antibodies created after vaccination.5

The diphtheria vaccine does not contain any blood products and is not a ‘live’ vaccine. The antigens are made synthetically and are not the real bacteria. They cannot replicate themselves or cause disease.

How effective is the diphtheria vaccine?

Most adolescents (96–99%) who have had their childhood and adolescent booster dose of the diphtheria vaccine develop enough infection-fighting cells (antibodies) to protect them against diphtheria into adulthood.6

Given most adults in Australia are never exposed to diphtheria, older adults may need further boosters to keep high levels of infection-fighting cells (antibodies).7,8

Will my adolescent catch diphtheria from the vaccine?

No, there is no risk that your adolescent will catch diphtheria, because the vaccine does not contain the live bacteria that cause the disease.

What are the common reactions to the vaccine?
  • Up to 77% of adolescents who get a booster dose of a vaccine that protects against diphtheria, whooping cough and tetanus experience mild discomfort or pain where the injection was given. This can last one or two days after receiving the vaccine.9
  • Less than 3% of adolescents who get a booster dose of a vaccine that protects against diphtheria, whooping cough and tetanus experience a high temperature or fever.9
Are there any rare and/or serious side effects to the vaccine?
  • The diphtheria vaccine is a combination vaccine that also protects against whooping cough. Less than 2% of adolescents can experience a large (extensive) amount of limb or arm swelling after receiving booster doses of the combination vaccine that protects against whooping cough. This reaction usually happens within 48 hours of vaccination, lasts for 1–7 days and then resolves completely.10
  • The vaccine for diphtheria also protects against tetanus. Around 0.0005–0.001% of tetanus toxoid-containing vaccine doses given (or 0.5–1 in 100,000 doses given) in adults are linked to a swelling or inflammation of a nerve in the arm (brachial neuritis) that causes weakness or numbness.11,12 The seriousness and length of time of this reaction varies on a case-by-case basis.
  • About 0.0001% (1 in 1,000,000) of people have an allergic reaction following vaccination that affects their whole body, called anaphylaxis. This reaction usually happens within 15 minutes of getting the vaccine and can be treated with an injection of adrenaline. People who have this reaction usually recover quickly and don’t experience any long-term effects.13

If your adolescent doesn’t seem to be getting better or you are worried about them, you can get help: 

  • from your doctor
  • at your nearest emergency department
  • by calling Healthdirect on 1800 022 222.
What impact has vaccination had on the spread of diphtheria?

The rate of diphtheria cases in Australia reduced after the introduction of the first diphtheria vaccine in 1932, and decreased further after an advanced vaccine was released in 1953.14,15,16

Chart: How vaccination has impacted the prevalence of diphtheria

Sources: (i) Chiu C, Dey A, Wang H et al. Vaccine preventable diseases in Australia, 2005 to 2007 Communicable Diseases Intelligence 2010;34;supplement December: S1-167; (ii) Australia’s notifiable disease status, 2010: annual report of the National Notifiable Diseases Surveillance System. Updated with data from NNDSS Annual Report Writing Group. Communicable Diseases Intelligence 2012;36:1-69

What if I still have questions?

You can read some answers to common questions here.

If you still have some questions about vaccinations for your adolescent, write them down and make an appointment with your nurse, your doctor or your health worker so you can ask them.

Please note: In SKAI Adolescent, the phrase ‘your adolescent’ refers to all guardian relationships where health decisions for an adolescent fall under your responsibility.

Drafts of this page were reviewed by members of our Consumer Advisory Group.


  1. World Health Organization. Diphtheria. September 2023. Available from https://www.who.int/news-room/questions-and-answers/item/diphtheria
  2. National Centre for Immunisation Research and Surveillance. Diphtheria is back in Australia, here’s why – and how vaccines can prevent its spread. July 2022. Available from https://ncirs.org.au/diphtheria-back-australia-heres-why-and-how-vaccines-can-prevent-its-spread
  3. Hempenstall A, Short J, Marquardt T et al. Clinician alert: toxigenic diphtheria cases across North Queensland are on the rise. The Medical Journal of Australia 2023;218:238
  4. Vitek CR, Wharton M. Diphtheria toxoid. In Plotkin SA, Orenstein WA, Offit PA (eds). Vaccines. Philadelphia: Elsevier: 2008
  5. Australian Academy of Science. The science of immunisation: questions and answers. 2021. Available from https://www.science.org.au/education/immunisation-climate-change-genetic-modification/science-immunisation
  6. World Health Organization. Diphtheria vaccine: WHO position paper – August 2017. Weekly Epidemiological Record 2017; 92:417-36
  7. Gidding HF, Backhouse JL, Gilbert GL et al. Immunity to diphtheria and tetanus in Australia: a national serosurvey. Medical Journal of Australia 2005;183:301-4
  8. World Health Organization. The immunological basis for immunization series: Module 2: diphtheria. April 2009. . Available from https://www.who.int/publications/i/item/who-immunological-basis-for-immunization-series-module-2-diphtheria
  9. Pichichero ME, Rennels MB, Edwards KM et al. Combined tetanus, diphtheria, and 5-component pertussis vaccine for use in adolescents and adults. JAMA 2005;293:3003-11. Erratum appears in JAMA 2005;294:3092
  10. Mertsola J, Van Der Meeren O, He Q et al. Decennial administration of a reduced antigen content diphtheria and tetanus toxoids and acellular pertussis vaccine in young adults. Clinical Infectious Diseases 2010;51:656-62  
  11. Hamati-Haddad A, Fenichel GM. Brachial neuritis following routine childhood immunization for diphtheria, tetanus, and pertussis (DTP): report of two cases and review of the literature. Pediatrics 1997;99:602-3
  12. Stratton KR, Howe CJ, Johnston RB, Jr. (eds). Adverse events associated with childhood vaccines: evidence bearing on causality. Institute of Medicine (US) Vaccine Safety Committee. Washington, DC; National Academy Press: 1994
  13. McNeil MM, Weintraub ES, Duffy J et al. Risk of anaphylaxis after vaccination in children and adults. Journal of Allergy and Clinical Immunology 2016;137:868-78
  14. Winkler NE, Dey A, Quinn HE et al. Australian vaccine preventable disease epidemiological review series: diphtheria 1999–2019. Communicable Diseases Intelligence 2022;46:1-6
  15. Chiu C, Dey A, Wang H et al. Vaccine preventable diseases in Australia, 2005 to 2007. Communicable Diseases Intelligence 2010;34;supplement December: S1-167
  16. Australia’s notifiable disease status, 2010: annual report of the National Notifiable Diseases Surveillance System. Updated with data from NNDSS Annual Report Writing Group. Communicable Diseases Intelligence 2012;36:1-69