The New York Times.
Doctors may have figured out why the covid-19 of AstraZeneca could cause some blood clots potentially lethal in very rare cases.
The discovery, made in a couple of reports published Friday in the online edition of the New England Journal of Medicine, could be key to the global deployment of the vaccine. AstraZeneca, by helping to develop effective treatments for side effects and provide clues on how to refine the vaccine to solve the problem, experts say.
But it could also prevent efforts to get the vaccine approved in the United States, where it already exists 3 vaccines available.
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the AstraZeneca vaccine it seems to make certain people develop some antibodies targeting a protein from the human body called platelet factor 4 (PF4), which causes platelets to go into action and a coagulation cascade, explained the co-author of the report, Dr. Theodore Warkentin, Professor of Pathology and Molecular Medicine at McMaster University in Ontario, Canada.
“It is a antibody that the vaccine activates in some way, and in some circumstances this results in an unusual coagulation of la sangWarkentin pointed out.
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secondary effects
The phenomenon is similar to a strange pharmacological side effect caused by heparin, an anticoagulant, and is known as heparin-induced thrombocytopenia, Warkentin noted.
The coagulation side effects of the vaccine are so uncommon that both the European Medicines Agency (EMA) and the UK Medicines and Healthcare Products Regulatory Agency have decided to keep it on the market. concluding that its benefits outweigh its risks, AstraZeneca noted in a statement.
However, the vaccine label will be updated to mention blood clotting as an extremely rare potential side effect.
“AstraZeneca has collaborated very actively with regulators to implement these changes in product information, and is already working to understand the individual cases, epidemiology, and possible mechanisms that could explain these events, which are extremely rare, “the company said in a statement.
As of April 4, the EMA had received reports of 169 cases of brain clots and 53 cases of abdominal clots among some 34 million doses of AstraZeneca that have been administered across Europe, according to Reuters.
In the UK, 19 people have died for blood clots vaccine-related seriousness, CNN reported.
Cases of clots are similar to what is sometimes reported with the anticoagulant heparin
worrying
Two of the three vaccines against COVID-19 being distributed in the United States (Pfizer and Moderna) have shown no such side effects. But on Friday, European drug regulators said they are reviewing reports of rare blood clots in four people who received the Johnson & Johnson COVID-19 vaccine. Of the four cases, three occurred in the United States during vaccine deployment and one person died, and the fourth case was reported in a clinical trial, according to CNBC.
One of the new reports on the AstraZeneca vaccine focuses on 11 patients in Germany and Austria who developed severe clotting problems after being vaccinated, while the other reviewed the cases of five care workers at the AstraZeneca vaccine. health, 32 to 54 years, who developed the side effect.
The tests revealed that all patients had developed PF4 blood clotting complexes similar to those caused by heparin, although none had received the anticoagulant.
These new findings do not yet give doctors any clue as to who could become ill from excessive clotting after receiving the AstraZeneca vaccine, Dr. noted. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee.
“So far, it’s focused on younger age groups, but we can’t determine in advance who these people are. The question will be, as we continue with public policy around the world, how will this vaccine be managed? ” , raised Schaffner.
But the findings could help target the treatment of people who develop symptoms similar to heparin-induced thrombocytopenia, Warkentin noted.
“If someone develops symptoms five or more days after the vaccine, either a headache or neurological symptoms, or an abnormal pain or shortness of breath, then the person who received the vaccine would know that they should seek medical attention.” , pointed out Warkentin. “Something just as important is that clinical professionals evaluating the patient would know how to look for him.”