Australia reports second blood clot case ‘likely’ linked to AstraZeneca Covid vaccine

Health authorities have concluded a second case of a rare blood clot syndrome in Australia “is likely” linked to the AstraZeneca vaccine.

The case occurred in a woman in her 40s who received the AstraZeneca Covid jab in Western Australia, the Therapeutic Goods Administration announced on Tuesday. She is receiving treatment in hospital and is in a stable condition.

Australia on Tuesday also recorded its 910th coronavirus death – the first since 19 October. The 80-year-old man contracted Covid-19 overseas and tested positive on day five of hotel quarantine in Queensland, before being transferred on 23 March to Prince Charles hospital, where he subsequently died.

Last Thursday, Australia’s vaccine rollout was thrown into disarray by an advisory slapped on the AstraZeneca vaccine warning people under 50 it may cause extremely rare but potentially deadly blood clots.

Related: AstraZeneca blood clotting: what is this rare syndrome and how is it caused?

Health authorities estimate the syndrome affects four to six cases per 1 million AstraZeneca vaccine recipients, but it can cause a death rate of up to 25% when it occurs. The Australian Technical Advisory Group on Immunisation, an independent group of medical experts that advises the health minister, said: “More cases can be expected to occur, albeit rarely.”

The TGA said its vaccine safety investigation group concluded on Monday that “a recently reported case of thrombosis with thrombocytopenia is likely to be linked to vaccination”.

John Skerritt, the head of the TGA, told reporters in Canberra the woman’s diagnosis was “complicated by some other conditions”.

Skerritt said deep-vein thrombosis and other forms of clotting “are extremely common” and were “not overtly contraindicated” – meaning they do not rule out a patient receiving the AstraZeneca vaccine.

“So it’s only if you’ve had a similar condition, related to an anticoagulant called Heparin, that people are saying ‘do not vaccinate those people’.”

The case is the second instance in Australia of blood clots believed to be linked to the AstraZeneca vaccine, after a 44-year old Melbourne man also developed the syndrome earlier in April.

“There have been about 700,000 doses of AstraZeneca Covid-19 vaccine administered in Australia to date, so while numbers are small, two cases … equates to a frequency of one in 350,000,” the TGA said.

“The UK regulator … has concluded from its review of cases reported in the UK that the overall risk of these rare blood clots was approximately one in 250,000 who receive the vaccine.”

The TGA said it used an “internationally accepted” method to rate the certainty of a link between the blood clots and the vaccine. It concluded “the case is similar to cases seen in Europe and the United Kingdom of a rare clotting disorder” because it included blood clots in the veins, low blood platelet count and blood test results consistent with other cases.

“Diagnosis was complicated by some ambiguous imaging findings and the need to run additional confirmatory blood tests.”

The TGA said common side-effects of Covid-19 vaccines included fever, sore muscles, tiredness and headache, and those were “not of concern unless severe or persistent”.

Related: Australia won’t buy Johnson & Johnson’s one-dose Covid vaccine due to AstraZeneca similarities

“The reports of these rare clotting complications have occurred later (between day four and 20 after vaccination) and have generally been severe, requiring hospitalisation,” it said.

The TGA advised people to seek medical attention if a few days after vaccination they experienced:

• Severe or persistent headache or blurred vision;

• Shortness of breath, chest pain, leg swelling or persistent abdominal pain; or

• Unusual skin bruising and/or pinpoint round spots beyond the site of injection.

The federal health minister, Greg Hunt, said 56,000 vaccinations had occurred in the past 24 hours despite some state programs being “paused or varied” to deal with the new AstraZeneca warning.

Asked if the warning had caused a spike in vaccine hesitancy, Hunt said health authorities “had anticipated potentially a significant drop but that is not what we have seen at this stage”.

The health minister said the federal government was meeting with the states to revamp the vaccination program for under-50s. “But what continues is the vaccination program for the over-50s – that remains as vital as ever,” he said. “Vaccinations save lives. Vaccinations protect lives.”

Earlier on Tuesday, Hunt’s office revealed Australia would not purchase Johnson & Johnson’s Covid-19 vaccine, citing concerns that it is an adenovirus vaccine of the same type as AstraZeneca.

There are similar concerns about the Johnson & Johnson vaccine, with Europe’s drug regulator reviewing rare blood clots in four people in the US who received the adenovirus vaccine.