In a briefing on Friday ahead of next week's World Health Organisation vaccine composition meeting in the French city of Lyon, avian viruses expert Michelle Wille took stock of Australia's ongoing H5 bird flu outbreak.
Dr Wille, an outreach co-ordinator at Melbourne's WHO Collaborating Centre for Reference and Research on Influenza, said it was impossible to predict how long Australia's first H5 wave could last.
"A key concern moving forward is that birds will aggregate for breeding, which could amplify what we're seeing," she said.
"Also, a lot of the ducks and water birds currently in Australia are in the centre given there's a lot of water in the interior, and so whenever they leave the interior to move back to the coast that could kind of amplify activity again.
"I really think it's uncertain as to how long this could last but I do think, based (on) what's happened everywhere else in the world, it's likely that the virus is here to stay."
There have now been 572 confirmed H5 bird flu events across Australia since it was first detected in June, including 301 in South Australia alone.
Under national protocols, H5 bird flu detections are reported as events rather than individual animal detections.
No events have been found in ducks but Dr Wille said they were critical movers of the virus throughout the northern hemisphere. Â
"In collaboration with Deakin University, since June we've been out catching as many ducks as we can all across Victoria," she said.
"The latest back-of-the-envelope calculation was more than 900 ducks have been sampled."
Another 900 samples have been taken from migratory shorebirds and seabirds across Australia since 2022 under a program that will resume in three weeks, Dr Wille said.
"We have seen mass mortality events in shorebirds elsewhere, particularly in Europe, where they've been infected by other wild birds," she said.
"Shorebirds globally are declining, and we've got some species of shorebirds here in Australia that are quite endangered.
"There's millions of them that come to Australia each year, which will expand essentially the population of coastal birds, so it is of course a risk."
The first detection of H5 bird flu in an Australian pelican, discovered at Edithburgh on SA's Yorke Peninsula, was confirmed on Monday.
A sea lion, found dead at Victor Harbour, was also sent for testing.
It came after the first Australian sea lion was confirmed to have died from the virus on Sunday.
With no suitable vaccine for threatened mammals, Dr Wille said researchers were monitoring for evidence of sustained transmission in sea lions.
"This has happened in South America as the virus moved with marine mammals along the coast," she said.
"We saw the emergence of mutations that facilitated mammalian transmission in sea lions, and so it's really critical for us to continue to do genomic surveillance of all of these cases."
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