Australia abruptly halted the production of a home-made vaccine against Covid-19 after trials showed it could interfere with HIV diagnosis, the developers said, with the government instead securing additional doses of rival vaccines.
The inoculation being developed by the University of Queensland (UQ) and vaccine maker CSL, one of four candidates contracted by the Australian government, was halted after "certain HIV diagnostic assays" returned false positives.
While there were no serious adverse effects seen in the Phase 1 trial of 216 participants, data showed antibodies that had developed interfered with HIV diagnosis and led to false positives on some HIV tests, CSL said.
Given the results, CSL said it had come to a decision with the Australian government to stop Phase 2 and Phase 3 trials of the vaccine.
"This outcome highlights the risk of failure associated with early vaccine development, and the rigorous assessment involved in making decisions as to what discoveries advance," said Andrew Nash, CSL's chief scientific officer.
The Australian vaccine could be re-engineered but doing so would take another 12 months.
"While this is a tough decision to take, the urgent need for a vaccine has to be everyone's priority," said Paul Young, a UQ professor who co-lead the vaccine project.
CSL will instead produce an extra 20 million doses of a vaccine developed by Britain's AstraZeneca Plc, on top of the 30 million it is already producing, while the government has also secured more doses of Novavax vaccines, with whom it already has supply contracts.
Australia also has an agreement with Pfizer for 10 million doses of its Covid-19 vaccine, with the country's regulator expected to approve it by January 2021.
"The University of Queensland vaccine will not be able to proceed based on the scientific advice, and that will no longer feature as part of Australia's vaccine plan," Prime Minister Scott Morrison told reporters on Friday.
All up, Australia has secured 140 million vaccine units to inoculate its 25 million people, one of the highest ratios of vaccine purchases to population in the world, officials said.
Australia's tally of 28,000 Covid-19 infections is far fewer than many other developed countries, and with only sporadic cases of the virus now showing up, it has not raced to start vaccinations as in North America and parts of Europe.
The country is scheduled to start vaccinations in March 2021 and expects to have its whole population inoculated by the end of that year.
National and state and territory leaders are scheduled to meet in person for the first time in nine months on Friday for their last cabinet meeting of the year to plan the vaccination roll-out.
Despite suffering significant economic hits due to Covid-19, Australian consumer sentiment is climbing again as the country re-emerges from the pandemic faster than most.
The north-eastern state of Queensland is the latest to relax further border measures, and will open to New Zealand travellers from Saturday, Queensland state Premier Annastacia Palaszczuk said on Friday.