The Australian government has updated advice on the rollout of the AstraZeneca COVID-19 vaccine after confirming a link between the jab and rare blood clots.

NEW ASTRAZENECA RECOMMENDATIONS

* The use of the Pfizer vaccine is preferred over AstraZeneca in Australian adults under 50 who have not already received their first AstraZeneca dose

* Australian immunisation providers should only give a first dose of AstraZeneca COVID-19 vaccine to adults under 50 where the benefit clearly outweighs the risk

* Australians who have had their first dose of the AstraZeneca vaccine without any serious adverse events can safely be given their second dose, including those under 50

* Australians who have had blood clots associated with low platelet levels after their first dose of the AstraZeneca vaccine should not be given a second dose

* Australia's Department of Health further develop and refine resources for informed consent that clearly convey the AstraZeneca vaccine's benefits and the risks


HOW WILL THIS AFFECT AUSTRALIA'S COVID-19 VACCINATION ROLLOUT?

* Rollout plan will be recalibrated and re-evaluated

* End of October timeline for every Australian to receive first vaccine dose in doubt

* Phase 1b - which includes younger adults with a medical condition or disability and frontline health workers among others - may be delayed

* Pfizer vaccine will be reprioritised for under 50s once phase 1a finishes

* Australia's vaccine purchases under review


HOW OFTEN DO ASTRAZENECA-LINKED BLOOD CLOTS OCCUR?

* Four to six cases per million AstraZeneca vaccine doses

* One known Australian case found in a 44-year-old man admitted to hospital in Melbourne

* 25 per cent death rate in known cases

* More common among younger people

* Cause unknown