Four of these cases have been confirmed, while two are considered probable but are still under investigation.
Among the most serious of the new cases is a 53-year-old man who is in Intensive Care in South Australia.
He received his first dose of the vaccine on Tuesday May 4 and was hospitalised two weeks later on Tuesday May 18 with severe abdominal pain.
South Australia’s Chief Public Health Officer, Professor Nicola Spurrier, said the man’s treating doctors recognised his symptoms immediately and began specialised treatment.
“Unfortunately, he is in a very serious condition in Intensive Care and my thoughts and thoughts from others in SA Health are with him and his family at the moment,” Professor Spurrier said.
“This is obviously of great concern, but it is not something that is not unexpected.”
Roughly one in 100,000 people who receive the AstraZeneca COVID-19 vaccine are expected to develop thrombosis with thrombocytopenia syndrome (TTS).
The rare but potentially fatal condition sees patients develop serious blood clots with a low blood platelet count.
Also among the newly confirmed cases is a 18-year-old woman from Queensland and a 57-year-old woman from Victoria.
An earlier case in a 79-year-old Victorian man has now been confirmed as related to the AstraZeneca shot.
Two other new cases – an 87-year-old South Australian woman and a 71-year-old woman from Victoria – were deemed probably related to the vaccine but inquiries are continuing.
It brings the total number of cases of TTS linked to the AstraZeneca vaccine in Australia to 24, of which 21 have been officially confirmed by the TGA.
Despite the growing tally, Professor Spurrier urged South Australians to continue to come forward for vaccination.
“People need to think about this one in 100,000 risk – there are risks to everything we do in life, and there are certainly risks to all medications,” she said.
“But we are still not out of the woods, absolutely, from COVID – you can see what has happened in India.
“There are other countries who were doing particularly well early on in the pandemic such as Taiwan and they are now experiencing increasing COVID cases.
“All of those countries have been a little bit slow off the mark with their vaccine roll outs.”
Around 2.1 million doses of the AstraZeneca vaccine have been administered so far across Australia.
Of Australia’s 24 cases of TTS linked to AstraZeneca, only one – a 48-year-old woman from New South Wales – has so far proved fatal.