Continuing diphtheria outbreak triggers CDINS declaration

In a statement released late last week, Australia’s Chief Medical Officer, Professor Michael Kidd AO, declared diphtheria a Communicable Disease Incident of National Significance (CDINS).

The declaration allows for enhanced coordination across all levels of government, enabling rapid deployment of vaccines, medications and workforce support, as well as nationally coordinated surveillance and public health guidance.

It follows the Government’s announcement of $7.2 million in funding.

Since the outbreak was first declared in the Northern Territory in late March, cases have spread to parts of Queensland, South Australia and Western Australia, with 267 cases – including one confirmed death – reported as at 29 May 2026.

Diphtheria is caused by toxin-producing Corynebacterium diphtheriae and, less commonly, C. ulcerans, which can infect the respiratory tract or the skin, resulting in 2 forms of infection:

• cutaneous (skin) diphtheria, with symptoms including skin ulcers
• respiratory diphtheria, with symptoms such as fever and sore throat. In severe cases, a pseumomembrane (grey-white patch) can form in the throat and may lead to airway obstruction.

Healthcare providers in outbreak areas are urged to be aware of these symptoms.

Vaccination can protect against severe diphtheria infections and reduce transmission of the disease. Diphtheria toxoid vaccine is included in the childhood immunisation schedule and is recommended and available for free under the National Immunisation Schedule (NIP) at 2, 4, 6 and 18 months, and 4 years of age.

A booster dose is recommended and NIP-funded for children aged 11–13 years.

While the vaccine is highly effective in infancy, immunity wanes over time. For this reason, a diphtheria booster is also recommended for adults aged 50 years and over, and for those aged 65 years and over, if more than 10 years have passed since their last dose.

As part of the outbreak response, NSW Health along with other states and territories, are commencing programs for free diphtheria vaccines (beyond those funded on the NIP) for eligible people.

NSW Health Northern and Central Australia Diptheria Outbreak 2026

Australians are recommended to check their vaccination status and receive a diphtheria booster if one is due.