- They think this kicks off a chain reaction, involving the immune system, that can culminate in dangerous clots.
- Some package that code up inside spheres of fat, while the AstraZeneca one used an adenovirus (specifically a common cold virus from chimpanzees) as its microscopic postman.
- AstraZeneca said the vaccine is thought to have saved more than a million lives around the world and prevented 50 million cases of Covid.
Scientists believe they’ve discovered “the trigger” for extremely rare blood clots following the Oxford-AstraZeneca Covid vaccination as reported by BBC.
Blood clots
The team, based in Cardiff and the United States, has demonstrated in minute detail how a protein in the blood is drawn to a vaccine component.
They believe that this sets off a chain reaction that involves the immune system and can result in deadly clots.
About a million people are expected to have been rescued from Covid thanks to the vaccine.
Concerns about uncommon blood clots, on the other hand, have affected how the vaccine has been used around the world, including in the United Kingdom, where an alternative is being offered to people under the age of 40.
It also sparked a scientific investigation into what was going on and whether it might be avoided.
To find the answers, the Cardiff team was awarded emergency government funds.
After the team’s initial findings were published, AstraZeneca’s own scientists joined the research endeavour.
A spokesperson for AstraZeneca underlined that clots were more likely to form as a result of the medication.
“While the data isn’t conclusive, it does provide fascinating insights, and AstraZeneca is looking into ways to use these findings as part of our efforts to eliminate this relatively rare adverse effect,” she continued.
For the researchers looking into the uncommon blood clots, there were two initial clues:
- Only particular vaccination technologies were found to have a higher risk of clotting.
- Antibodies against platelet factor four, a protein in the blood, were found in people with clots.
Adenovirus
In order to train the immune system, all vaccines used in the UK attempt to transfer a snippet of the Covid-genetic virus’s code into the body.
Some of the packages coded inside fat spheres, while the AstraZeneca one used an adenovirus (a common cold virus found in chimps) as its microscopic messenger.
The adenovirus was assumed to be associated with the uncommon clots that occur in some persons, according to the researchers. They utilised a method called cryo-electron microscopy to acquire molecular-level photographs of the adenovirus.
Their findings, which were published in the journal Science Advances, show that the adenovirus’s outer surface attracts the platelet factor four protein like a magnet.
“The adenovirus has a highly negative surface, and platelet factor four is extremely positive, and the two things fit together rather nicely,” Prof Alan Parker, one of the researchers at Cardiff University, told BBC News.
Misplaced immunity
“We’ve been able to prove the link between adenoviruses’ primary smoking guns and platelet factor four,” he added. “We have the trigger, but there are a lot of other things that need to happen.”
The researchers believe the next stage is “misplaced immunity,” but further research is needed to validate this.
The body is thought to fight platelet factor four after mistaking it for a piece of the foreign adenovirus with which it is infected. Antibodies are released into the bloodstream, where they clump together with platelet factor four and cause deadly blood clots to develop.
This, however, necessitates a chain of bad occurrences, which may explain why clots are so uncommon.
Out of almost 50 million AstraZeneca doses administered in the UK, these clots, termed vaccine-induced immune thrombotic thrombocytopenia, have been connected to 73 deaths.
“You could never have predicted that, and the chances are vanishingly small,” said Prof Parker, “but we need to remember the wider picture of how many lives this vaccination has saved.”
AstraZeneca
According to AstraZeneca, the vaccination is likely to have saved more than a million deaths and avoided 50 million cases of Covid over the world.
“We continue to follow any new developments and investigation into potential causes for these very rare side effects associated with the vaccine with interest,” a University of Oxford spokesperson said, “while being reassured by real-world effectiveness data that the vaccine remains a highly effective tool for combating this pandemic.”
The “extremely comprehensive” research, according to Dr Will Lester, a consultant haematologist at University Hospitals Birmingham NHS Trust, helps explain the “most likely early phase” in clotting.
“Many topics remain unsolved, including whether certain people are more sensitive than others and why thrombosis (clotting) is more common in the veins of the brain and liver,” he noted.
The Cardiff researchers intend to utilise their results to develop adenovirus-based vaccines in the future, lowering the risk of these rare incidents.
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Source: BBC
