Australia's medicine regulator has identified a second case of rare blood clots believed to be linked to the AstraZeneca vaccine.
The Therapeutic Goods Administration released a safety alert announcing the possible link on Tuesday.
The blood clots affected a woman aged in her 40s who was vaccinated in Western Australia.
"The person remains in hospital receiving treatment and is in a stable condition," the regulator said.
The rare but potentially deadly blood-clotting disorder recently resulted in the AstraZeneca vaccine being no longer recommended to any Australians aged under 50, derailing the national vaccine rollout.
It is the second Australian report of a case of rare blood clots after a 44-year-old Melbourne man developed the condition following his AstraZeneca vaccination last month.
Expert advisers to the TGA have concluded the latest incident is similar to blood clotting cases seen in Europe and the United Kingdom.
There have been about 700,000 doses of AstraZeneca vaccines administered in Australia, so the two cases equate to a frequency of one in every 350,000 people.
The United Kingdom has found the overall risk of these rare blood clots was approximately one in 250,000 people who received the vaccine.
People who have received the AstraZeneca vaccine have been asked to look out for symptoms including severe or persistent headaches, blurred vision, shortness of breath, chest pain, leg swelling or abdominal pain.
Symptoms also include unusual skin bruising and pinpoint round spots beyond the site of injection.
Meanwhile, the federal government has decided against buying the one-dose Johnson and Johnson coronavirus vaccine to boost the nation's immunisation stocks.
The government was in talks with the pharmaceutical giant, which had asked for initial approval for its vaccine from Australia's medicine regulator.
But Health Minister Greg Hunt has ruled out proceeding with the purchase at this stage because it is too similar to the AstraZeneca drug.
"The Janssen vaccine is an adenovirus vaccine, the same type of vaccine as the AstraZeneca vaccine," he said through a spokesperson.
"The government does not intend to purchase any further adenovirus vaccines at this time."
Johnson and Johnson also required a no-fault compensation scheme before it would sell vaccines to Australia, which the government was not committed to introducing.
Labor health spokesman Mark Butler said it was not good enough for the minister to announce his decision through a spokesperson.
Mr Butler wants to know the reasons behind the decision, saying Australia needs to secure more vaccine deals.
"With this very important vaccine that's rolling out through the US, will start to roll out through the United Kingdom very soon, if there is a decision not to go with it, what are the reasons for that?" he told the ABC.
"I think this is the problem Australians and Australian businesses are having right now - the communication channels from the government have shut down.
"We've got a prime minister that's retreated to Facebook and a minister who's making announcements through a spokesperson without clear background information."
Australian Associated Press