A 44-year-old man was admitted to a Melbourne hospital with clotting days after receiving the AstraZeneca vaccine, suffering serious thrombosis and a low count of platelets, or blood cells that stop bleeding.
“Investigators have not at this time confirmed a causal link with the Covid-19 AstraZeneca vaccine, but investigations are ongoing,” the deputy chief medical officer, Michael Kidd, told a televised briefing.
More was expected to be known on Saturday, he added.
On Thursday, Britain identified 30 cases of rare blood clot events following use of the vaccine, and several nations, including Canada, France, Germany and Spain, limited its use after similar reports.
Australian regulator the Therapeutic Goods Administration (TGA) has said previously the AstraZeneca vaccine was not tied to an increase in overall risk of blood clots, however.
In a statement on Friday, the Australian Technical Advisory Group on Immunisation said: “There is not a higher overall rate of relatively common types of blood clots (…) reported after Covid-19 vaccination.”
Australia launched mass vaccinations for its 25 million people in February, with most expected to receive the University of Oxford/AstraZeneca vaccine.