Australian vaccine experts will meet again on Saturday to discuss a Melbourne man’s blood clots as experts around the world try to uncover whether there is a causal link to the AstraZeneca COVID-19 vaccine.

The Therapeutic Goods Administration is investigating what’s thought to be the first Australian vaccine recipient affected by an “extremely rare” blood clotting disorder detected in a few dozen people who received the Anglo-Swiss drug maker’s jab.

Though rare, the disorder does occur naturally and after weeks of investigation, no evidence has emerged that the vaccine is the cause of recent rare clots that have been reported in Europe, the UK and now Australia.

A US trial review board has raised concerns about AstraZeneca vaccine data
The TGA is investigating the clotting. (AP)

Links of this sort can take months or more to properly investigate and Europe’s regulator does report seeing more of the rare brain clots than would be expected.

But the European Medicines Agency, having looked into 62 cases reported worldwide by March 22 at an incidence of 4.8 per million doses, points out the benefits of the vaccine far outweigh any potential risk. 

It also notes that COVID-19 itself often causes blood clotting disorders, further complicating attempts to clarify the situation.

Emer Cooke, the head of the European Medicines Agency, at the European Medicines Agency building in Amsterdam, the Netherlands, Friday Nov. 13, 2020
Emer Cooke, the head of the European Medicines Agency. (AP)

“According to the current scientific knowledge, there is no evidence that would support restricting the use of this vaccine in any population,” EMA executive director Emer Cooke said.

She said the EMA’s experts had not determined any underlying risk factors for the blood clots or established a causal relationship to the AstraZeneca vaccine.

“The link is possible, and we cannot say any more than that at this point,” Ms Cooke said.

What’s the situation in Australia?

In Australia, acting Chief Medical Officer Professor Michael Kidd said more than 425,000 doses of the AstraZeneca vaccine had been administered.

“One case of this clotting disorder has been recorded in Australia overnight and we are taking this very seriously,” Professor Kidd said.

“Investigators have not at this time confirmed a causal link with the COVID-19 AstraZeneca vaccine but investigations are ongoing.

“Central venous sinus thrombosis is a very rare disorder that is previously not been known to be associated with vaccination, however it has been noted as a complication of people who have contracted COVID-19.”

Deputy Chief Medical Officer Professor Michael Kidd said the TGA was investigating after a Melbourne man was hospitalised with blood clots after receiving the AstraZeneca vaccine. (9News)

He recommended Australians who experienced serious symptoms after receiving the AstraZeneca vaccine to seek medical help.

Those were more likely to be common side effects such as fever, sore muscles, tiredness and headache within 24 hours of getting the jab but could also include anaphylaxis, a known rare reaction to vaccinations in general, shortly after.

He said anyone suffering, “severe, persistent headache or other worrying symptoms, 4-20 days after the vaccine” should seek medical help immediately.

The TGA vaccine safety investigation group is meeting on Saturday to examine the issue.

How has this story developed over the past month?

German officials have decided to limit the use of AstraZeneca’s coronavirus vaccine in people under 60 after more unusual blood clots were reported in a small number of people who received the shots.

But the seesawing back and forth in some countries on who can take the vaccine has raised concerns its credibility could be permanently damaged. Here’s a look at what we know — and what we don’t.

What happened in Germany?

Earlier this week, Germany’s medical regulator released new data showing a rise in reported cases of unusual kinds of blood clots in people who recently got a dose of the AstraZeneca vaccine. 

“It’s about weighing the risk of a side effect that is statistically small, but needs to be taken seriously, and the risk of falling ill with corona,” Mr Spahn said.

Some 2.7 million doses of AstraZeneca have been administered in Germany so far. 

An employee prepares AstraZeneca’s Coronavirus vaccine for vaccination at the police vaccination centre in Munich, Germany. (AP)

Germany’s medical regulator said its tally of the rare blood clots reported by March 29 had increased to 31. 

Nine of the people died and all but two of the cases involved women, who were aged 20 to 63, the Paul Ehrlich Institute said.

Some clots have also been reported elsewhere among the tens of millions of people who have received the AstraZeneca vaccine.

What have previous investigations found?

It recommended a new warning be added to the vaccine’s leaflet and continued to authorise it for people 18 and over.

The EMA is looking closely at two rare types of blood clots, including one that affects the brain, reported in people who got at least one dose of the AstraZeneca vaccine and could update its recommendations for the vaccine next week.

On Wednesday, Dr Peter Arlett of the EMA said the agency was seeing “more cases of (brain clots) than we would expect to see.

He noted more younger women have been affected but it wasn’t clear if that was significant since younger women were also more likely to receive the AstraZeneca vaccine in Europe. 

He did not say how many of these kinds of clots would typically show up in the general population.

Emer Cooke, the agency’s executive director, said its experts had not been able to identify specific risk factors for those who might be at higher risk for the rare clots.

The World Health Organisation’s expert committee also evaluated available data for the AstraZeneca vaccine and said the shot was safe and effective. 

On Wednesday, WHO vaccines department head Dr Kate O’Brien, said it was continuing to review the situation.

It’s normal to continue to look for side effects as new vaccines are rolled out since they are typically tested in tens of thousands of people but some rare problems might only occur once millions receive the shot.

How can scientists figure out if there is a link between the two?

“The way to tell if cases are caused by vaccination is to look to see if there is an excess of cases in people who have been vaccinated,” said Dr Peter English, past chair of the British Medical Association’s public health medicine committee.

Adam Finn, a professor of paediatrics at the University of Bristol, said there was no compelling evidence yet that the vaccine was to blame for the rare clots.

“The mechanism by which these blood clotting abnormalities come about, and why they affect this very small proportion of individuals, has still not been properly worked out,” he said in a statement.

In a statement, AstraZeneca said it was analysing the tens of millions of records for people who received its vaccine “to understand whether these very rare cases of blood clots … occur any more commonly than would be expected naturally (in a) population of millions of people.”

What does this mean for COVID-19 vaccinations?

It’s bad news. Health officials worry the repeated suspensions and restrictions for the AstraZeneca vaccine could undermine confidence in a shot that is key to global efforts to stamp out the pandemic since it’s cheaper and easier to store than some others.

In Norway, which recently extended its suspension of the AstraZeneca vaccine for three weeks, officials say the confusion is prompting a wave of vaccine hesitancy.

The leader of the Norwegian Association for General Practice, Marte Kvittum Tangen, told broadcaster NRK that resuming vaccination with AstraZeneca “will be very difficult if we want the greatest possible vaccination coverage in the population in the long run.”

Professor Finn said the biggest health threat to the world currently was COVID-19 and any doubts about the effectiveness of authorised coronavirus vaccines were problematic.

“We need to stay focused on the need to prevent (COVID-19) taking millions more human lives before it is brought under control and the only effective way to do that is through vaccination,” he said.

This content first appear on 9news

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