Federal health authorities say five more cases of a rare blood clotting syndrome linked to the AstraZeneca Covid-19 vaccine have been identified in Australia.
The AstraZeneca vaccine (file image). Photo: Soumyabrata Roy/NurPhoto/AFP
Another three possible cases are under investigation, but authorities suspect they are unrelated to the vaccine.
There are now 11 Australian cases of blood clots which are believed to have been caused by thrombosis with thrombocytopenia syndrome, or TTS.
Therapeutic Goods Administration (TGA) head John Skerritt said the rate of people developing the syndrome in Australia was comparable to other countries.
"I would say the rates in Australia are very similar to those both publicly and confidentially reported to us in places like Canada, UK and continental Europe," he said.
"This is a rare adverse event but we believe it's staying at the expected frequency and at the frequency that we're seeing internationally."
Professor Skerritt said "many" of the 11 cases reported so far were in people with underlying medical conditions, but didn't go into detail about what those conditions were.
"Even though this is an area of very active medical research throughout the world, and I want to add that people with underlying clotting conditions do not seem to be at risk," he said.
"A lot of these people did have other serious conditions but there's not a common thread."
Latest cases all aged over 50, but authorities 'not surprised'
The five new cases of clotting confirmed by the TGA are two women, aged 51 and 64, and three men aged 66, 70 and 74.
The 66-year-old man is in intensive care in Townsville with thrombosis after receiving his first AstraZeneca dose on March 30, and the 70-year-old man is in a stable condition in hospital in Tasmania.
Professor Skerritt said while the AstraZeneca vaccine was recommended as safe for people over 50, the reaction was not unheard of in people in that age group in trials and elsewhere around the world.
"If you step back and think about who is now getting the AstraZeneca vaccine, it is, with a few rare exceptions, only people over 50," he said.
"So it is obvious that future cases will be in the over 50s.
"The early results globally showed that the prevalence of this rare side effect was much more common in people under 50, but it wasn't unknown in people over 50.
"So we're not surprised with the results."
In early April, Prime Minister Scott Morrison announced that the AstraZeneca Covid-19 vaccine would no longer be recommended for people under 50 based on the risk of developing the rare clots.
All Australians over 50 became eligible for the AstraZeneca vaccine on Monday.
Professor Skerritt said health authorities had also investigated Australian cases of clots in vaccine recipients where it turned out there was no link between the jab and the clotting.
"Sadly, blood clotting, including fatal blood clotting, is actually quite a common cause of serious illness and death in Australia," he said.
"It's also responsible for about 10 per cent of the deaths of people who die when they're admitted to hospital, and sadly never get out.
"So this is a common, serious thing that happens to people for a whole lot of reasons."
- ABC