Diphtheria outbreak in Australia: Debunking myths about the disease and vaccines

A diphtheria outbreak has spread to multiple states and territories in Australia, with one death in the Northern Territory so far likely caused by the disease.

The highly contagious bacterial infection was once a major cause of childhood deaths, before widespread vaccination programs in the 1930s dramatically reduced cases in Australia.

Falsehoods about the worsening outbreak are now spreading just as quickly online as the disease.

ABC NEWS Verify has taken a look at some of the claims and mistruths circulating on social media about diphtheria.

Myth: 'Migrants are to blame'

The idea that immigrants are somehow responsible for this current outbreak has been a recurring theme, but it's one likely based in xenophobia rather than reality.

Adelaide University professor of biostatistics and epidemiology in the School of Public Health, Adrian Esterman, said diphtheria had existed in Australia for a long time.

"Diphtheria is one of those diseases that people can carry without any symptoms and so it's likely been circulating in Aboriginal communities for a long time," he said.

"It just so happens that every now and then when the vaccine coverage dips slightly, or there's a bit of disruption, it takes off. So it's almost certainly got nothing to do with immigrants."

Raina MacIntyre, head of the biosecurity program at the University of New South Wales's Kirby Institute, said the location of the outbreaks revealed a flaw in the argument it was being spread by immigrants.

"It's exacerbated in some of these remote towns and communities because the vaccination rates might be a bit lower there than in the big cities."

Myth: 'Vaccines are more dangerous than the disease'

This is a common false claim that our experts were keen to dispel. Professor MacIntyre said the diphtheria vaccine was one of the safest and oldest vaccines medical professionals used.

"It's been around for decades and decades. It's one of the very first childhood vaccination programs that was rolled out," she said.

"The triple antigen, the diphtheria, tetanus and whooping cough vaccine, was the first rolled out in the WHO's [World Health Organization's] expanded program on immunisation. It's been used for so long, there's enormous amounts of data and it's a really safe vaccine."

She said this kind of fear and misinformation around vaccines peaked during the COVID-19 pandemic and was continuing to cause huge issues.

"The reason that we had misinformation about vaccines skyrocketing after COVID is it's the first time since the eradication of smallpox that the whole population has needed a vaccination," Professor MacIntyre said.

"That's never happened in most people's lifetime where you had to go and get a vaccine to go to the cinema, to go to work, to get on an airplane.

"So there's a general pushback against vaccines, with specific disinformation about mRNA vaccines, and that has actually affected all the other vaccines and it's dropped the confidence in all vaccines. That's the fundamental problem."

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Myth: 'Anti-vaxxers are solely to blame for this outbreak'

This one is slightly more nuanced. Professor Esterman told ABC NEWS Verify that some other factors had to be taken into consideration, including health inequality and access in remote areas.

"It's just that many of them live so far away from a health centre that they don't get the treatment and boosters they need."

However, Professor MacIntyre did lay the majority of blame on anti-vaxxers and vaccine sceptics who emerged in the wake of COVID.

"When you look at the timeline of this epidemic, you can see it start to rise after 2020 [and] after 2025 it's really gone up," she said.

"The remoteness and the healthcare access hasn't changed. That's not the factor that's changed that can explain this epidemic.

"The factor that has changed is the falling vaccination rates."