A preservative in the AstraZeneca vaccine could cause an immune system overreaction that leads to blood clots, a scientist claims.
A small number of people who got the shot or shot from Johnson & Johnson developed a clotting disorder that scared some countries to turn their backs on it.
The reasons for this are unclear, but a researcher in Germany has suggested it could start with a chemical used to make the vaccine.
EDTA, scientifically known as ethylenediaminetetraacetic acid, can cause an overreaction of the immune system by forming clumps with the help of platelets in the bloodstream.
Commonly used in medicines, cosmetics, cleaning products and metal processing, EDTA can cause more of the vaccine ingredients to leak into the blood vessels – the injection is delivered into the muscle.
There, they can cause the body to make excess antibodies and trigger a second immune system response, which then starts to clot blood.
Medical regulators at the MHRA in the UK have noted 242 cases of clots after 28.5 million doses of the AstraZeneca shot in 22.6 million people – about one in 100,000.
The blood clots remain rare and are much less of a risk than Covid, but people under 40 have been advised to take a different vaccine if they can.
The AstraZeneca Covid vaccine remains one of the most widely used in the world because it prevents serious Covid and is widely available, but some countries have limited its use to only older people with a higher risk of coronavirus which is greater than the risk of side effects ( photo: A nurse in Dublin fills a syringe with vaccine)
“The benefits of the Covid-19 vaccine AstraZeneca against Covid-19, with the associated risk of hospitalization and death, still outweigh the risks for the vast majority of people,” said MHRA director Dr. June Raine last week.
WHAT IS THE THEORY?
Dr. Greinacher’s theory depends on events that could be triggered by the EDTA preservative in the AstraZeneca vaccine, Pharmaceutical technology reports:
- EDTA increases the amount of vaccine proteins that leach into the blood from the muscles;
- Proteins from the vaccine work together with naturally circulating platelets to form clumps, activating the platelets;
- Platelet activation releases another protein (platelet factor 4 or PL4) that sticks to vaccine proteins, including virus fragments;
- The presence of PL4 and proteins in the blood causes the release of antibodies by the immune system;
- Large numbers of anti-PL4 antibodies cause a greater immune response, which may include inflammation (swelling) and increased blood clotting in some people.
‘The balance between benefits and risks is very favorable for the elderly, but it is better balanced for young people.
“We recommend taking this evolving evidence into account when considering the use of the vaccine.”
The government chose to make the policy of giving adults 40 or younger a choice of vaccines when they go to their appointment, because the percentage of low platelet blood clots was more common in them, in about one in 60,000 people.
The rollout of the NHS has expanded to 38 and 39 year olds for the first time today.
One of the main theories as to why the clots happened was that the body overproduction of antibodies that triggered a reaction that led to blood clotting.
Now Dr. Andreas Greinacher, a blood expert and immunologist at the University of Greifswald, may be able to explain why, Pharmaceutical technology reports.
Dr. Greinacher and his colleagues conducted studies in mice and suggest that EDTA causes proteins in the vaccine fluid to leak into the bloodstream and activate platelets by bumping into them.
Platelets are small components of clots and always circulate in the blood in case they are needed to heal an injury.
But as soon as they kick in, they start a chain reaction of immune responses, releasing another protein, known as PL4, that sticks to more proteins from the vaccine and starts forming more clumps.
These clumps then alarm the immune system and antibodies – not the Covid types – are produced to destroy them.
DOCTORS CLAIM THEY FOUND A TREATMENT FOR VACCINE BLOOD CLOTS
Doctors say they may have discovered a life-saving cure for the type of blood clots associated with Covid vaccines.
Doctors in Aurora, Colorado, were trying a blood thinner known as bivalirudin when a 40-year-old woman developed a blood clot in her brain two weeks after she received the J&J vaccine.
Not only did the drug help break up the woman’s blood clots, but she was able to leave the hospital and go home just six days later.
Several days earlier, the Centers for Disease Control and Prevention had advised doctors not to use the blood-thinning medication heparin.
This is because the condition – blood clots in addition to a low platelet count – is very similar to a condition that can be caused by heparin, called heparin-induced thrombocytopenia.
The new condition is called vaccination-induced thrombocytopenia.
Medical chiefs have not yet announced standard treatment for people who are diagnosed, although usual blood clot treatments will likely be used.
Large amounts of these antibodies then cause a higher immune system response, including swelling in the blood vessels and blood clots, potentially leading to clotting seen in vaccine patients.
Most notable cases were in a vein coming from the brain, a condition known as CVST, but the majority of cases in the UK (149 out of 242) were elsewhere in the body.
In the UK, a total of forty-nine people have died after developing a blood clot after vaccination.
Some countries, including Denmark and Norway, have completely stopped using the AstraZeneca vaccine, while others have restricted it to older people.
Last week, health officials in the UK said people under 40 should be offered an alternative to the injection as the risks and benefits were well balanced.
For older people who have a real risk of dying if they receive Covid, the benefits of protecting against the virus clearly outweighed any negative side effects.
Experts said the infection rate in the UK is now so low that the risk of the rare blood clots is greater than Covid’s in younger adults, who often have only mild disease.
Instead, they will be offered the Pfizer or Moderna vaccines, as long as there is an adequate supply and it does not delay the rollout.
Anyone, regardless of age, who has received the first dose of the AstraZeneca shot and has not suffered the complication is urged to come forward for their second.
England’s deputy chief physician Professor Jonathan Van-Tam claimed the change would not affect the government’s goal of vaccinating all adults by July 31.
“Our vaccine delivery schedule will support the change without limiting the speed and scale of vaccine rollout,” he told a television news conference in Downing Street.
“I do expect we are still on track to provide a first dose to all adults by the end of July.”
Earlier, on April 7, it was recommended to offer healthy young people under 30 an alternative to AstraZeneca.