Australia is facing a major delay in its coronavirus vaccine rollout after new bombshell advice plunged the program into chaos.
Health supremos have recommended not administering the AstraZeneca vaccine to people under 50 because of an extremely rare but serious blood clot side effect.
The advice destroys the Morrison government's October rollout target with the immunisation effort not likely to be completed until 2022.
Prime Minister Scott Morrison said the program would be recalibrated over the weekend as officials come to grips with the new development.
"The overall impact of this on the timetable of the rollout, it is far too early," he told reporters just minutes after receiving the advice on Thursday night.
Australia was relying on AstraZeneca jabs to the backbone of coronavirus immunisations through 50 million locally produced doses.
Labor has lambasted the government for failing to secure more deals with other vaccines successfully being rolled out to millions of people worldwide.
Opposition frontbencher Kristina Keneally labelled the development a debacle and a negative game-changer.
"This just means Australians are going to wait months and months, possibly even another year, before life resembles anything like normal," she told ABC radio on Friday.
"That failure sits on Scott Morrison's head."
More people under 50 will now receive the Pfizer jab with health workers pushed to the front of the queue.
But Australia has a contract for only 20 million doses - enough for 10 million people - and less than one million have been delivered.
The government's immunisation advisory group made the cautious decision after blood clots linked to the AstraZeneca vaccine were mostly associated with younger people.
The reaction has appeared in four to six people for every million to receive the jab, with a 25 per cent death rate for people who develop the syndrome.
A man in his 40s who was admitted to hospital in Melbourne is the only person in Australia to develop the problem.
People who have already received their dose of AstraZeneca have been given the green light for a second jab with clotting only detected after the first shot.
Others under 50 could also be administered the jab if consultation with a doctor determined benefit outweighed risk.
AstraZeneca noted Australia's decision factored in having no community transmission of the virus.
"Overall, regulatory agencies have reaffirmed the vaccine offers a high-level of protection against all severities of COVID-19 and that these benefits continue to far outweigh the risks," it said in a statement.
The advice compounds the federal government's headaches with the rollout already under fire for lagging behind most other developed nations.
While 51 million doses of the promising Novavax vaccine could be injected into the effort from October, that jab is yet to gain approval anywhere in the world.
© AAP 2021
Image: Prime Minister Scott Morrison (AAP Image/Mick Tsikas)