Home / World / AstraZeneca vaccine linked to rare blood clots, EU regulators concluded.

AstraZeneca vaccine linked to rare blood clots, EU regulators concluded.



Close-up shot of a small transparent bottle
Expand / A vial of AstraZeneca COVID-19 vaccine was seen during the opening of a vaccination center in Cyprus on March 22, 2021.

European medical regulators on Wednesday concluded that there is a strong link between AstraZeneca’s COVID-19 vaccine and life-threatening conditions associated with an abnormal combination of blood clots and platelet levels. low

Therefore the condition should be stated as The “very rare side effect” of the vaccine, according to the European Medicines Agency, the European Union’s regulator.

This conclusion comes from the EMA’s in-depth review of 86 coagulation events among some 25 million people who received AstraZeneca vaccine in Europe and the UK. Of the 86 blood clotting events, 18 died, most, but not all, in women under the age of 60.

Events investigated by the EMA included 62 cases of intracerebral venous thrombosis (CVST), a rare form of stroke in which the clot prevents blood from bleeding from the brain. The remaining 24 were involved in intravenous thrombosis, involving a blood clot in a vein that drains blood from the abdomen.

In addition to the 86-case investigation, the EMA estimated that there was a reported rate of one case of side effects in 100,000 vaccinated people.

Cause I want to know

Surprisingly, coagulation events are accompanied by low levels of platelets, which are pieces of blood cells that clump together. Typically, low platelets will cause increased bleeding, not clotting. The regulator noted that this unusual combination resembles a condition known as heparin-induced thrombocytopenia, or HIT. In coagulation, a decrease in platelet count is seen. But it goes into excessive bleeding, which can lead to coagulation and widespread death.

HIT is developed as a result of an abnormal immune response. In a completely incomprehensible reaction to heparin, some patients’ immune systems produce antibodies that attack a common platelet protein called Platelet Factor 4, or PF4.This triggers the activation of platelets and their binding particles. Clot which leads to HIT

Some researchers suspect that a coagulation event linked to AstraZeneca’s vaccine might produce the same berserk immune response and possibly even treat it. Extremely preliminary information posted online But it has not been published in a journal or peer review, suggesting that a rare condition in some vaccines can be treated with non-heparin anticoagulants, including immunoglobulins. High doses of linolines have been shown to inhibit platelet aggregation. Stimulation in HIT patients

In an announcement on Wednesday, the EMA noted that it was important to recognize the early signs of blood clots and low platelets, and that getting specific treatment quickly could avoid potentially fatal outcomes.

The EMA notes that newly vaccinated people should be aware of:

  • Shortness of breath
  • Chest pain
  • Swelling in your legs
  • Persistent abdominal (abdominal) pain
  • Neurological symptoms include severe and persistent headache or blurred vision.
  • Tiny blood spots under the skin other than the injection site

As seen in people who developed HIT after receiving heparin, the coagulation and low platelet aggregation events seen in the vaccine usually occurred within two weeks of the first dose.

Although the EMA solidifies the connection between the blood clot and the AstraZeneca vaccine, the vaccine is still recommended. “Reports of a combination of blood clots and low platelets are extremely rare,” the agency said. “And the overall benefit of the vaccine against COVID-19 outweighs the risk of side effects.”

Dramas AstraZeneca

The conclusion came weeks into the vaccine, with more than a dozen countries that allowed it to suddenly stop vaccination with blood clot concerns and then resume using it again without concern. The COVID-19 epidemic

In addition to the EMA, the World Health Organization maintains a strong assertion that the efficacy of AstraZeneca vaccine against the life-threatening COVID-19 infection outweighs the risks of very rare coagulation disorders.

However, Germany made a move last week to limit the use of the vaccine in people under 60, the age group with the rarest coagulation events. But not all And on Tuesday, Oxford University, which co-developed the vaccine with AstraZeneca, said it had temporarily halted trials of the vaccine in children and adolescents in the UK.

Meanwhile, AstraZeneca is still mired in communication. In the latest erroneous step, the company has encountered a serious disorder and is involved in an altercation with a panel of U.S. experts tasked with overseeing the COVID-19 vaccine trial and data. The Information and Safety Examiner claims that AstraZeneca had picked up the cherry-picked results in its press release that could mislead the public about the vaccine’s true efficacy.

The company has defended its actions. But it has not yet sent information to the U.S. Food and Drug Administration for approval for its emergency use. Last week, infectious disease expert Anthony Fauci suggested that although it was banned. But the US may not need AstraZeneca’s vaccine because enough of the three vaccines currently authorized for use will be provided in the United States.

Problems for Johnson & Johnson

The new EU list of side effects will only make AstraZeneca harder. And it is also likely to create a shadow over Johnson & Johnson’s COVID-19 vaccine, which is licensed in the United States and elsewhere and uses the same variant as AstraZeneca’s vaccine.

Both vaccines use adenovirus vector.Adenoviruses are common viruses that can cause cold-like infections and other mild ailments in people.For vaccine delivery, they are designed not to recreate in cells or Cause disease But can pass the genetic code of more dangerous pathogens to the cell In the case of the COVID-19 vaccine, engineered adenoviruses transmit code of the SARS-CoV-2 spike protein adorned on the outside of the virus particle. The spike protein is what SARS-CoV-2 uses to bind into human cells and inward, and is a prime target for potent antibodies and immune responses. When an adenovirus vector transmits code for a spike, our cells can make their own versions of the protein and use it to train the immune system’s response to recognize and destroy the SARS-CoV-2 virus.

The potential bug with adenovirus vaccines is that adenoviruses can bind to platelets and cause problems. In fact, some pre-epidemic data suggest that adenoviruses can activate platelets and lead to low platelet counts. But the link between this and vaccines and the mechanisms by which blood clotting occurs in vaccines requires more information to understand.

However, the side effects seen in AstraZeneca’s vaccine raise concerns about Johnson & Johnson’s during the Johnson & Johnson vaccine clinical trials showing early signs of an increased risk of coagulation in people who have. Get the vaccine, EMA chief data analysis Peter Arlett said in a news conference on Wednesday. But Link was never confirmed, he added.

Of the approximately 4.5 million people who received the Johnson & Johnson vaccine worldwide, three cases with a coagulation event were reported similar to those seen in people who received the AstraZeneca vaccine, Arlett said, these numbers. “Very little,” he stressed, “however, this is under close scrutiny … I think it will be fair to say that this issue is being investigated intensely throughout the vaccine.”


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