Researchers are hailing the release of RHDV-K5 an early success, with rabbits in every mainland state now confirmed to have died from the disease.

The Korean strain of the Rabbit Haemorrhagic Disease was rolled out at about 600 sites in all mainland states and the ACT in the first two weeks of March.

Researchers at the CSIRO in Canberra have analysed 80 samples from dead rabbits over the weeks since the release — and 53 per cent of those samples have tested positive to the new RHDV-K5 virus.

"It's very, very early days," said release national co-ordinator Tarnya Cox.

"But it is successful in that we are having rabbits die from K5."

The national K5 release locations. ( Supplied )

Dr Cox, based at the NSW Department of Primary Industries in Orange, said the positive samples came from the official release sites, indicating the rabbits were most likely infected by the baits laced with virus.

"When there are rabbits dying off site, then we can say it has been truly successful," she said.

That would mean the virus was being spread by flies from the carcases of dead rabbits to other live rabbits.

Confirmed cases of K5, as of March 29, 2017. ( Supplied )

The release of RHDV-K5 came after almost a decade of research. It was chosen in part because it works better in cool, wet regions — the climate zones where the previous Calicivirus was not so effective — and tests show it does not affect other animal species.

The RSPCA, which broadly supports humane feral rabbit control, had pushed to delay the rollout of K5.

"We would have preferred the release to have been delayed," said RSPCA chief scientist Bidda Jones.

She said the animal welfare body was concerned by how another virus circulating and killing rabbits, RHDV2, would interact with the new K5 strain.

Dr Jones also wanted pet rabbit owners and breeders to have had more time to vaccinate their animals.

"It's really important that anyone with a pet rabbit or farmed rabbits vaccinates all their rabbits," she said.

"The vaccine protects against the existing strain of RHD, it appears to protect against K5, although there is more work to be done in that area."

Dr Tanja Strive at the CSIRO tests for K5. ( ABC News: Prue Adams )

The currently available vaccine does not completely protect against the RHDV2 — the strain that mysteriously arrived from Europe two years ago and has now killed tens of thousands of rabbits across the country.

Dr Cox said anyone finding dead rabbits should log the location on a phone and tablet app, called Feral Scan, and ask for a sampling kit to be sent out.

Those reporting dead rabbits can send liver or bone samples from the animals to the CSIRO for analysis.

The results of those tests will be relayed back to the reporting land manager and uploaded to the www.feralscan.org.au website.

Watch the story on Landline, Sunday at noon on ABC TV.