As vaccine-makers scramble to retool their products, a team of researchers working between the US and UK believes it has found the “trigger” that causes extremely rare blood clots in some patients.
The side effects, first exposed over the spring and summer, have hurt sales of the UK-developed jab, which was a collaboration between AstraZeneca and Oxford University.
According to scientists, who published their findings in the journal Advances, a protein in the blood is attracted to certain ingredients in the vaccine. This phenomenon can kick off a chain reaction involving the immune system that sometimes culminates with the production of dangerous blood clots.
Despite this, AZ has sought to play down fears about the clots, since regulators in the UK, Australia and Europe (though notably not the US) have approved the jab, insisting that risks of these “rare” blood clots was far outweighed by the protections it offered the vaccinated. However, the jab has often come with restrictions, like in the UK, where the government has asked those under 40 to take a different vaccine.
Now, the world is learning once again that breakthrough infections are much more common than they were initially told. What’s more, scientists are still trying to determine whether omicron can surpass protections offered by the jabs and natural infection from earlier variants.
Most insist that infections with this new variant are mostly mild, especially since several vaccinated individuals have reportedly been infected and suffered only minor symptoms.
As for the AstraZeneca jab’s blood clots, the BBC has created a diagram purporting to illustrate how the process works:
In its report, the BBC added that there were two initial clues for the researchers investigating the rare blood clots:
- The greater risk of clots was seen only with some of the vaccine technologies
- People with clots had unusual antibodies that were attacking a protein in their blood called platelet factor four
So far, all vaccines used in the UK work by delivering a kernel of genetic code from SARS-CoV-2 into the body to train the immune system. Some jabs package that code up inside spheres of fat, while the AstraZeneca jab uses an adenovirus (specifically a common cold virus from chimpanzees) as its microscopic postman.
Ideally, this breakthrough should help AZ tweak its vaccine to eliminate this side effect – assuming that’s even possible. But it’s also reminder that vaccine-makers are still working to refine their product to eliminate these rare but dangerous side effects.