The Western Australia (WA) Department of Health reports expanding its diphtheria outbreak vaccination program to include the Midwest, and extended vaccine eligibility to all Aboriginal people across the State, as part of its ongoing response to the outbreak in regional Western Australia.
The expansion aims to improve protection against severe illness due to diphtheria among Aboriginal people and other eligible groups at increased risk of exposure.
There have now been 170 cases reported across the Kimberley, Pilbara and Goldfields regions, predominantly among Aboriginal people.
Most cases have occurred in the Kimberley (135 cases), with additional cases reported in the Pilbara (31 cases) and the Goldfields (four cases). There is also evidence of diphtheria transmission in the Midwest.
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Of the 170 cases reported, 104 have involved cutaneous (skin) infections and 66 have involved respiratory (throat) infections, including two severe respiratory cases.
Director Communicable Disease Control Directorate Dr Paul Armstrong said while most cases involved skin infections, respiratory diphtheria remained the more pressing public health concern.
“Diphtheria is a serious bacterial infection that can affect the skin or throat,” Dr Armstrong said.
“While most recent cases in Western Australia have involved skin infections, severe respiratory diphtheria can be life-threatening and can lead to complications.
“Our priority is to identify cases early, support affected communities, increase vaccination coverage and reduce the risk of further spread of the disease.
“Vaccination remains the best defence against severe illness due to diphtheria, which is why it is so important for people to ensure they are protected.”
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Vaccination activities are already underway in the Kimberley, Pilbara and Goldfields, and have now begun in the Midwest following the expansion of the vaccination program.
The response focuses on catch-up vaccination for children and adolescents under the National Immunisation Program, alongside vaccination of eligible adults who have not received a diphtheria-containing vaccine in the past five years.
Almost 15,000 doses of diphtheria-containing vaccine, supplementing those funded under the National Immunisation Program, have already been distributed across the outbreak-affected regions, with additional supplies available as required.
Diphtheria-containing vaccines are now available for people who have not received a diphtheria-containing vaccine in the past five years and who:
are an Aboriginal person living anywhere in Western Australia
reside in the Kimberley, Pilbara, Goldfields or Midwest regions
have regular face-to-face contact with Aboriginal communities in the Kimberley, Pilbara, Goldfields or Midwest regions, including patient-facing healthcare workers and other frontline workers who work, but do not reside, in these regions.
Diphtheria was previously very rare in Australia due to high vaccination rates and improved living conditions – respiratory diphtheria had not been seen in WA for more than 50 years.
Nationally, a total of 413 cases of diphtheria have been notified in Australia in 2026, including 410 confirmed cases and three probable cases, including Northern Territory and South Australia.