Bird flu hits Oz. What next? And why should I get a (human) flu shot?

Adam Spencer
13 minutes ago
6 min read

Australia was the last continent on Earth free of the bird flu strain that has killed wildlife by the million. As of mid-June 2026, that run is over. Here is what it means, and why the sensible response might involve a human flu shot.

The belnded Northern Star Trail above Kitt Peak. — ('Australia breahced': created via Dall-E)

(First published on my Substack where you can get #NerdNews, marvellous maths and general geekery.)

Worldwide outbreak hits our shores.

On 14 June a brown skua, a big bullying seabird of the Southern Ocean, washed up skinny and dehydrated in the seaweed at Cape Le Grand beach near Esperance in Western Australia.

Within a week, testing at the CSIRO confirmed what authorities had been bracing for. The bird had H5N1, the highly pathogenic bird flu that has spent the past few years carving its way through the planet's wildlife. A second seabird found nearby, a giant petrel, is suspected positive too.

This is an unfortunate first. Australia was the last continent on Earth without a confirmed mainland case of this strain clade 2.3.4.4b, (yes, including Antarctica!).

It has been spreading globally since about 2021 and everywhere it has gone the story has been grim. In the United States more than 200 million domestic birds have died or been culled since 2022, sending egg prices through the roof.

On our own sub-Antarctic Heard Island it is estimated to have killed about 13,000 southern elephant seal pups in a single breeding season, roughly three-quarters of the pups born there, and conservationists now fear for Australia's own crowded seabird colonies.

So how did the last holdout finally fall?

As so often happens with disease spread, our geography bought us time.

Australia sits clear of the big northern flyways that carried the virus across the top half of the world, so it could not simply barge in the front door.

Instead it came the back way, drifting down through the sub-Antarctic and Heard Island, then north on the wings of a seabird built to cross the Southern Ocean. The skua and the petrel are exactly those long-haul travellers, which is why the first case turned up on a wild and windy WA beach, nowhere near a poultry farm.

So what is bird flu?

Bird flu, or avian influenza to the geekier among us, is a flu virus that lives, mostly harmlessly, in wild waterbirds. Ducks and their relatives carry it along the world's migratory flyways, shedding it into the water and mud other birds use. Most strains are mild but some highly pathogenic ones like H5N1, coloured yellow below, are not.

CDC/Cynthia Goldsmith (Jacqueline Katz; Sherif R. Zaki), Public Health Image Library #1841. Public domain.

In chickens it can kill most of a flock within a few days, which is why an infected farm is culled. Given there is no cure, stamping it out fast is the only way to stop it racing onward.

And as the sea-lion carnage on Heard Island showed, it is not just a bird problem. The virus has spilled into foxes, seals, sea lions, cats, dogs, dairy cattle and even zoo tigers.

It first grabbed the world's attention in Hong Kong in 1997, when it leapt straight from chickens into people, infecting 18 and killing six. More than 1.5 million chickens were slaughtered to shut it down.

Since then experts have been on heightened alert for outbreaks of avian flu.

"Every spillover into a new host is an evolutionary trial." — Associate Professor Vinod Balasubramaniam, Monash University.

But humans can't get it yeah?

Yeah ... nah ... actually we can.

And while only a handful of people have caught it so far, we have to be really careful here.

To see why it is rare, you need to know how a flu virus breaks in.

Bird flu gets into cells using a protein called haemagglutinin. Think of a key which has to fit a matching lock on your cells, sugar molecules called sialic acid receptors, which come in two shapes. Bird flu is cut to fit the α2,3 receptors that line a bird's gut. Human flu fits the α2,6 receptors in our nose and throat.

H5N1 mostly carries the wrong key for us. The receptors it does fit sit deep in our lungs, not up in the nose and throat where a virus takes hold and spreads most readily. That mismatch is a major reason it is hard to catch from birds, and harder still to pass from one person to the next.

When humans do catch it, it takes close, sustained contact with infected animals, almost always on farms.

Here’s the good news. Fewer than 100 human infections with this recent H5N1 clade were recorded worldwide between 2021 and early 2025, despite its enormous spread through birds and mammals.

And of around 70 human cases in the United States during this outbreak, only one has so far died of H5N1: a Louisiana man with underlying health problems who kept backyard chickens.

So the current clade looks far less lethal for humans than the roughly 50 per cent death rate seen in earlier H5N1 strains overall.

But with COVID fresh in our minds, we all know that as flu viruses replicate they can mutate. Remember Delta, Omicron and the other Greek letters we suddenly became experts in? Bird flu mutates too, and one of the great fears is a strain that learns to spread easily between humans.

For years when it comes to human risk the villain has been the pig, whose airways carry both receptor types, letting bird and human flu meet and trade genes. But US dairy herds are also worth keeping a close eye on. They keep the virus in daily contact with farm workers, and in the lab some cattle virus samples grip both the bird lock and the human lock at once.

"Low public risk must not be mistaken for low biological significance." — Associate Professor Vinod Balasubramaniam, Monash University.

So what do we do?

Think of the response in three parts, and none of them call for panic.

The federal government has been preparing for years. It has more than 100 response plans for high-risk sites and threatened species, and has tipped well over $100 million into readiness, from farm biosecurity to wildlife vaccination. A national response to the WA detection is already under way.

Farmers are on high alert, the poultry industry most of all, where a single incursion near a commercial shed could be devastating. If you keep backyard chooks, and plenty of people around Esperance do, the advice is to keep them away from wild birds, secure their feed and water, and watch for sudden unexplained deaths.

And the rest of us? If you come across a sick or dead wild bird, don't touch it, keep your dogs and cats well away, and report it to the Emergency Animal Disease Watch Hotline on 1800 675 888. That is the single most useful thing an ordinary person can do. Early reporting is exactly how Australia spotted this bird in the first place.

And a final wrinkle involving the human flu shot. A seasonal flu jab will not protect you against H5N1, but what it can do is lower the odds of you catching human flu and bird flu at the same time. In that scenario the two could swap entire gene segments inside you, a process called reassortment, and assemble something new and dangerous.

Australia's Centre for Disease Control has urged people to get vaccinated for that very reason.

"The current public health risk is low." — US Centers for Disease Control and Prevention.

So should I be freaking out? And can I still eat eggs?

I can understand people's concerns, but yes, eating properly prepared chicken and eggs carries no risk of you getting bird flu. Avian influenza is not a foodborne illness, and ordinary cooking destroys the virus.

Worth saying plainly: at the time of writing, no infection has been found in any Australian poultry, so our eggs and chook are not even coming from sick flocks.

The advice is boring. Cook your eggs. Cook your chicken. Don’t eat weird raw birds.

As for the bigger question. There is no need to be alarmist here. But accurate, reasonable perspectives matter. On one hand this virus is not good at spreading between humans, and recent human cases have mostly been mild. On the other, experts have warned for decades about the danger of an international pandemic, especially a flu-driven one.

While Dustin Hoffman in Outbreak had a healthy dash of Hollywood about it, the fact remains that the 1918-19 "Spanish Flu" pandemic killed an estimated 20 to 50 million people worldwide, possibly more, likely outstripping the toll of the entire First World War, in a horribly painful fashion.

Be alert. Don't yet be alarmed. And think about that flu shot.

Bird flu hits Oz. What next? And why should I get a (human) flu shot?

Worldwide outbreak hits our shores.

So what is bird flu?

But humans can't get it yeah?

So what do we do?

So should I be freaking out? And can I still eat eggs?

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