New York Times.
Doctors may have learned why against the vaccine covid-19 from AstraZeneca could cause some blood clots potentially fatal in very rare cases.
The discovery, made in a pair of reports published Friday in the online edition of the New England Journal of Medicine, could be the key to the global launch of the vaccine. AstraZeneca, helping to develop effective treatments for side effect and give clues on how to refine vaccine to solve the problem, experts say.
But it could also hamper efforts to get the vaccine approved in the United States, where it already exists. three vaccines available.
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AstraZeneca vaccine it seems to cause certain people to develop antibodies targeting a protein from body called platelet factor 4 (PF4), which triggers platelets in action and activates Coagulation cascade, explained co-author of the report Dr. Theodore Warkentin, a professor of pathology and molecular medicine at McMaster University in Ontario, Canada.
“And antibody that the vaccine is activated in some way and, in certain circumstances, this results in unusual coagulation of theblood“Warkentin pointed out.
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Side effects
The phenomenon is similar to a rare side effect caused by heparin, an anticoagulant known as heparin-induced thrombocytopenia, Warkentin noted.
The side effects of vaccine coagulation are so rare that both the European Medicines Agency (EMA) and the UK Agency for the Regulation of Health Products and Products have decided to keep it on the market, concluding that its benefits outweigh its risks, he noted. AstraZeneca in a statement.
However, the vaccine label will be updated to mention blood clotting as a potentially extremely rare side effect.
“AstraZeneca has been very active in working with regulators to implement these changes to product information and is already working to understand the individual cases, epidemiology and possible mechanisms that could explain these extremely rare events,” he said.
As of April 4, the EMA had received reports of 169 cases of brain clots and 53 cases of abdominal clots among about 34 million doses of AstraZeneca that were administered across Europe, according to Reuters.
In the UK, 19 people have died as a result blood clots serious vaccine-related injuries, CNN reported.
Cases of clots are similar to what is sometimes reported with thin blood heparin
Anxious
Two of the three COVID-19 vaccines distributed in the United States (Pfizer and Moderna) had no such side effects. But on Friday, European drug regulators said they were examining 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 implementation 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 analyzed the cases of five health workers between the ages of 32 and 54. years, which developed the side effect.
Tests showed that all patients developed PF4 blood clotting complexes similar to those caused by heparin, although none received anticoagulant.
These new findings do not yet give doctors any clues as to who may be suffering from excessive clotting after receiving the AstraZeneca vaccine, said Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee.
“So far, it has focused on younger age groups, but we can’t determine in advance who those 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 guide treatment for people who develop symptoms similar to heparin-induced thrombocytopenia, Warkentin said.
“If someone develops symptoms five or more days after the vaccine, whether it’s a headache or neurological symptoms, or abnormal pain or difficulty breathing, then the person who received the vaccine would know to seek medical attention,” he said. said Warkentin. It is equally important that clinicians who evaluate the patient know how to look for them.