Why Australia should urgently vaccinate wildlife most at risk from H5N1 bird flu

Source: The Conversation (Au and NZ)

Australia has confirmed deadly H5N1 bird flu has been found in 102 wild seabirds across five states at the time of writing, including the country’s first mass death of birds.

The question is no longer if this virus can harm Australian wildlife, but whether we should use every available tool to protect species most at risk.

Vaccination cannot stop H5N1 spreading through wildlife. But it could prevent an outbreak from killing all of the at-risk species in an area – a tragic local extinction.

Australia should begin targeted vaccination of threatened birds. It should also urgently develop a strategy for seals and sea lions, rather than waiting until thousands are dead.

A policy exists, but action remains too cautious

Australia has a national policy that allows emergency vaccination of rare, protected and valuable birds, including animals in zoos, sanctuaries, breeding programs and some managed wild populations.

The government has also purchased an inactivated H5 vaccine – containing no live virus – and is running pilot studies in captive non-poultry birds.

This is important groundwork, but not yet a public program comparable with New Zealand’s ambitious and proactive approach to vaccinate five of the country’s rarest birds before the arrival of H5N1.

Australian zoos and sanctuaries have received funding to strengthen biosecurity and captive “insurance populations”. Pilot vaccinations are underway, but the government has not announced which threatened species will receive wider vaccination, where, or when.

More importantly, the policy excludes non-avian (bird) species, meaning marine mammals are not considered despite their known vulnerability to H5N1. No plans have been announced to the public for Australian vaccination trials for seals or sea lions.

What overseas programs show

New Zealand prepared before H5N1 arrived. After species-specific trials, it began vaccinating about 300 core breeding birds of rare species, including kākāpō, takahē and black stilts. These are captive or closely managed populations whose individuals can be found, vaccinated twice and monitored.

The United States acted after H5N1 killed 21 critically endangered California condors. By October 2024, 207 captive and free-flying condors had been vaccinated. The vaccine was judged safe, although two birds had treatable adverse reactions.

France has conducted a vaccine trial in wild king penguin chicks on the French sub-Antarctic island of Crozet. The vaccine produced strong, virus-neutralising antibodies without detected adverse effects.

These programs do not prove vaccination will prevent every infection. But it could lessen severe disease and reduce the number of animals that die in threatened populations.

Which species should Australia vaccinate?

Broadscale vaccination of free-ranging wildlife is unrealistic. Most H5 vaccines require two doses, and most wildlife is difficult to capture once, let alone being recaptured for a booster and blood test.

The best candidates are small populations of at-risk species that are either easily accessible or already under management. For example, threatened birds in zoos or breeding centres, or small, known colonies with tracking or regular handling.

On Tuesday, the Australian government released a list of at-risk species, that showed almost one-in-five Australian bird and mammal species is at high, very high or extreme risk from the virus.

Five bird species are at extreme risk – the Christmas Island frigate bird, Houtman albatross, Herald petrel, imperial shag on Heard Island and imperial shag on Macquarie Island. The marine mammals most at risk are the sea lion, fur seal and elephant seal, while the Tasmanian devil and eastern quoll are the highest risk species on land.

Decisions must balance extinction risk, exposure to the virus, cost, vaccine performance, whether enough animals can be reached, and whether capture would cause unacceptable stress. Vaccination must sit alongside existing biosecurity, surveillance and conservation measures – not replace them.

Australia needs a seal plan

H5N1 has decimated seal and sea lion populations across South America and the Southern Ocean. More than 17,000 southern elephant seal pups were killed in Argentina in 2023. An estimated 13,359 pups died at the Australian sub-Antarctic Heard Island in 2025, believed to be from the virus. Southern elephant seals were listed as vulnerable on the IUCN Red List in April, in part because of the catastrophic mortality caused by bird flu. It will take decades for these populations to recover.

Australia’s most vulnerable seals include the endangered Australian sea lion, Australian and long-nosed fur seals, and southern elephant seals. H5N1-positive terns have already been found at Seal Bay on Kangaroo Island, home to a major Australian sea lion breeding colony. Southern elephant seals have a large breeding colony on Australia’s sub-Antarctic Macquarie Island, which remains free of H5N1 at this time.

There is currently no bird flu vaccine designed specifically for marine mammals. A United States trial aimed at protecting endangered Hawaiian monk seals found a vaccine developed for cattle was safe in northern elephant seals and produced measurable antibodies.

This was the closest comparable species for which a safe, conditionally licensed vaccine was available. Developing and approving a separate vaccine for every wildlife species is costly and time-consuming, so conservation programs commonly adapt vaccines already approved for domestic animals.

Now is the time to act

Australia should identify priority seal colonies now, trial candidate vaccines in a suitable surrogate species and plan how vaccination could be deployed. We should not wait to learn how susceptible these animals are by watching more mass deaths unfold.

Vaccination is not a silver bullet. But when a disease can erase years of conservation work in weeks, we should not wait for perfect certainty. It’s time to act before catastrophe.

Jane Younger receives funding from the Australian Research Council, National Geographic Society, Rolex, WIRES, the Marine Megafauna Research Fund and Lindblad-National Geographic. She is affiliated with the University of Tasmania.

Original source: https://analysis1.mil-osi.com/2026/08/05/why-australia-should-urgently-vaccinate-wildlife-most-at-risk-from-h5n1-bird-flu/