After the AstraZeneca vaccine has been associated with an atypical blood clot disease, Johnson & Johnson, based on the same technology, it is the target of the same suspicions. What is known about it so far?
What was observed?
In both cases, suspicions arose after detecting multiple cases of thrombosis in vaccinated people.
These are not simple thromboses, such as phlebitis, but very unusual conditions. First, because of their location: they affect the cerebral veins and to a lesser extent the abdomen, the European Medicines Agency (EMA) reported on April 7. AstraZeneca
With the vaccine Johnson & Johnson “Cerebral sinus venous thrombosis” was also seen, the US health authorities, the FDA and the CDC said Tuesday.
These pathologies occur along with a decrease in the number of platelets, so that the patient can bleed at the same time as blood clots.
The EMA first acknowledged on April 7 that these problems could be caused by the vaccine from AstraZeneca
In contrast, this relationship has not yet been formally established with the vaccine Johnson & Johnson, licensed but not yet managed in Europe under the name Janssen. In the United States, his job was suspended on Tuesday pending a scientific response.
What is this for?
These problems may be related to the technique of both “viral vector” vaccines. This is based on taking a different virus for support, which has been modified so that it carries genetic information in the body that can fight COVID.
Both use an adenovirus, a very common type of virus. The one of AstraZeneca is a chimpanzee adenovirus and that of Johnson & Johnson it’s human.
“Everything indicates that it is due to the adenovirus vector,” Mathieu Molimard, a French pharmacology specialist, explained on Twitter, recalling that these kinds of problems do not occur with the Pfizer / BioNTech and Moderna vaccines, which contain the messenger RNA. use technique.
It is not yet known whether these diseases are also registered with another vaccine that uses adenovirus, the Russian Sputnik V. This is authorized in about 60 countries, but not in the European Union or the United States.
What are the mechanisms?
Several elements indicate an over-immune response caused by these vaccines COVID-19
In a study published online March 28, German and Austrian researchers established a comparison with a different known mechanism.
The phenomenon “clinically resembles heparin-induced thrombocytopenia (HIT),” said the team of scientists led by Andreas Greinacher from the University of Greifswald.
HIT is an unusual, serious, and abnormal immune response caused in some patients by an anti-coagulant, heparin.
It’s a “plausible explanation,” the EMA ruled on April 7, pushing for new studies.
What is the risk?
This is the most important question. According to figures from the EMA, 222 cases of atypical thrombosis had been detected on April 4 after 34 million injections of AstraZeneca in the 30 countries of the European Economic Area (EU, Iceland, Norway, Liechtenstein) and the United Kingdom. With a balance of 18 dead through March 22.
The thrombosis occurred “during the two weeks after vaccination,” according to the EMA.
In case of Johnson & JohnsonUS authorities registered six cases, including one death, among more than 6.8 million doses administered, and symptoms occurred between 6 and 13 days after the injection.
But as with all medications, it’s important to weigh the risks and benefits.
“The global benefits of the vaccine in the prevention of COVID-19 outweigh the risks of side effects, ”said the EMA AstraZeneca
What risk factors are there?
At the moment, most cases are with AstraZeneca they occurred in “women under 60,” according to the EMA. The six cases discovered in the United States with Johnson & Johnson they were women between the ages of 18 and 48.
But it is too early to draw any conclusions. For now, “we have not identified any specific risk factors,” the EMA said about it AstraZeneca
After the first wave of suspensions, in mid-March, some countries decided to stop using the vaccine below a certain age: 30 years in the UK, 55 years in France, Belgium and Canada; 60 in Germany and the Netherlands, and 65 in Sweden and Finland.
“We don’t just have one vaccine, we have several. That’s why it seems logical to me to reserve the vaccine for AstraZeneca elderly, ”Sandra Ciesek, a virologist at Goethe University in Frankfurt, told Science magazine.
The UK authorities have released a chart showing that the COVID-19 poses a health risk six times greater than the vaccine between the ages of 20-29. But in the 60-69 age group, the risk is 600 times more important.
Norway and Denmark chose to stop using the vaccine completely AstraZeneca
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