Tasmania has halted first-dose injections of the AstraZeneca COVID-19 vaccine for people aged under 50 years, following federal health advice.
The decision comes after Prime Minister Scott Morrison late on Thursday received recommendations from the Australian Technical Advisory Group on Immunisation.
The ATAGI recommended the Pfizer vaccine be "preferred" over the AstraZeneca vaccine in people under 50, who face a very slight risk of developing blood clots.
"The Tasmania government has put an immediate hold on any first dose AstraZeneca vaccinations of people aged under 50 years," the state government said in a statement.
People with first dose AstraZeneca appointments are being contacted to reschedule their vaccine.
The state department of health is contacting the 1400 people aged under 50 who have received a first AstraZeneca dose and asking them to be aware of symptoms.
Premier Peter Gutwein said the state's vaccine rollout would require some "recalibration" after the latest advice.
"In terms of what this change means for Tasmania's planned vaccine rollout, we are working our way through that," he told reporters on Friday.
Mr Gutwein, who is in the midst of a state election campaign, will on Friday join his interstate counterparts and Mr Morrision for a national cabinet meeting to discuss the vaccine rollout.
Tasmania's Public Health Director Mark Veitch said the state's rollout would be slowed in the short term.
"It's really important we get the rollout right. Obviously we cant get the vaccine to everybody at once and we ask people to be patient," he said.