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Scientists Find How AstraZeneca Vaccine Causes Clots

InternationalScientists Find How AstraZeneca Vaccine Causes Clots

April 22, 2021 — Scientists in Germany say they’ve worked out the two-step mechanism by which the AstraZeneca vaccine causes rare but devastating blood clots that gobble up the body’s supply of platelets.

So far, European regulators have reported more than 220 cases of unusual blood clots and low levels of platelets in patients who received the vaccine, called Vaxzevria, which was developed with funding from the U.S. government’s Operation Warp Speed program to spur development of a suite of vaccines to protect people from COVID-19. AstraZenecaThe AstraZeneca vaccine has not yet been authorized for use in the United States.

“This is, in my opinion, rock-solid evidence,” said Andreas Greinacher, MD, head of the Institute of Immunology and Transfusion Medicine, University Hospital Greifswald, Germany, who was among the first scientists in the world to link the rare clots to antibodies against a key protein in platelets.

“This is what scientists usually think is confirmatory evidence,” he said in a call with reporters hours after publishing his study as a preprint ahead of peer review on the Research Square server.

Greinacher said he felt an urgent need to get the information out as soon as possible. He said his team had worked around the clock for 5 weeks to get answers, “because we are in the middle of the vaccination campaign. This was the driving force for us and the big motivation to provide these data as fast as any other possible,” he told reporters on the call.

Greinacher said that he believes the mechanism linking the vaccine with the rare clotting reactions is likely to apply to other vaccines that also use adenoviruses to ferry instructions for making the virus’s spike protein into cells.“My assumption is, and that’s a hypothesis, that this is a class effect of vaccines using adenovirus,” he said. He added that he could not be certain because he only studied reactions to the AstraZenecaAstraZeneca vaccine. But previous studies have shown that adenoviruses can cause the type of platelet activation he saw in the reactions he studied.

Greinacher said that he had worked out an agreement with Johnson & Johnson about an hour before the call to collaborate on studying its COVID-19 vaccine. The company had previously been unwilling to share information, he said. The J&J vaccine is also adenovirus-based.

At least seven cases of the same pattern of unusual clots have been documented in people who received the one-dose Johnson & Johnson vaccine. Over 7 million Johnson & Johnson vaccines have been given in the United States so far.

While the reactions are extremely rare, they can be serious. One person, a 45-year-old woman in Virginia, has died. That led the CDC and FDA to call for a pause on administering the Johnson & Johnson vaccine last week. The company also announced that it would hold clinical trials to get more answers about the reactions.

In his new study, Greinacher and colleagues describe a series of events that has to happen in the body before the vaccines create these large clots. He explained that while everyone has the basic immune machinery that leads to the unusual clots, it is almost always kept in balance. The body uses a series of checks to prevent any step in the process from getting out of control.

In some cases, however, there’s a perfect storm where each stage progresses to the next and the end result is very hard to control. That autoimmune attack, which causes the body to go into a hyper-clotting state, typically burns itself out after a few weeks. So if patients can get rapid treatment, the condition nearly always goes away.

He said he only knew of one case of an autoimmune syndrome like this lasting 10 years, but that was in a patient who had taken the blood thinner heparin, which can cause a nearly identical syndrome.

This full article can be viewed at: https://www.webmd.com/vaccines/covid-19-vaccine/news/20210422/scientists-find-how-astrazeneca-vaccine-causes-clots

This article was first published by www.webmd.com

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