The AstraZeneca vaccine was born destined to change the course of the pandemic. The drug, developed by the University of Oxford (United Kingdom), was 100% effective against severe covid in clinical trials, can be stored in normal refrigerators and costs just three euros per dose, about five times less than the from Pfizer and seven times less than that of Moderna. The Anglo-Swedish pharmaceutical AstraZeneca has pledged to distribute non-profit 3 billion doses this year, including to the poorest countries on the planet. But there is an obstacle on this path back to normal life: the presumed association of the vaccine with the formation of blood clots in exceptional cases.
The European Medicines Agency is investigating 44 cases of these rare thrombi – with 14 deaths – after more than nine million injections. Italian pharmacologist Marco Cavaleri , head of the agency's Vaccine Strategy, explained on March 29 that these “very infrequent events,” in which thrombus formation and a low blood platelet level are combined, “have occurred. in about one person in a million and are under investigation. " A committee of the European agency is meeting this week to re-analyze the situation , although Cavaleri himself stated this Tuesday in the Italian newspaper Il Messaggero that "it is clear that there is a link with the vaccine, which causes that reaction." Some European countries already decided days ago to restrict the use of the injection, such as Germany, which only administers it to those over 60, and France, which only does so with those over 55.
"It is clear that there is a link with the vaccine," said pharmacologist Marco Cavaleri, from the European Medicines Agency.
Clots associated with the injection of AstraZeneca in the EU have been observed mainly in women under 55 years of age, but the European Medicines Agency stresses that this could be due, at least in part, to the fact that vaccination campaigns were started with the health and educational personnel, made up mainly of female workers.
The pharmacist Jesús Sierra has taken up accounts. With the data on the table, for every million vaccinated with AstraZeneca, 120,000 infections, 4,100 hospital admissions and 800 deaths from covid would be avoided, but there would be one or two cases of these strange thrombi supposedly induced by the vaccine, according to Sierra's calculations, worker at the University Hospital of Jerez de la Frontera (Cádiz) and spokesperson for the Spanish Society of Hospital Pharmacy
The European Medicines Agency already ruled on March 18 that the AstraZeneca vaccine is not associated with a generalized increase in the risk of clots blood in vaccinated people. The body did recognize then that the drug "could be associated with very rare cases" of thrombus formation, including cerebral venous sinus thrombosis , a disorder in which the clot hinders blood circulation in the brain. The European agency ruled that the benefits of the vaccine continue to outweigh this minimal risk of adverse reactions. On March 19, a committee of the World Health Organization came to the same conclusion .
Disturbing cases in the UK are also rare. Britain's drug regulatory agency, the MHRA, is studying 22 cases of cerebral venous sinus thrombosis and another eight of other thromboses, following more than 18 million injections of AstraZeneca as of March 24. "The benefits of vaccines against covid continue to outweigh any risk and you should be vaccinated when invited to do so," prompts the British body in a statement updated on April 1.
The Spanish Society of Angiology and Vascular Surgery urges citizens to get vaccinated without fear
The vascular surgeon Rodrigo Rial , 58, is forceful. “That people continue to be vaccinated without fear. I have put the AstraZeneca one on and I would put it on again ”, says Rial, president of the Spanish Chapter of Phlebology of the Spanish Society of Angiology and Vascular Surgery. His organization, which deals with venous pathologies in Spain, issued a statement on Monday encouraging citizens to get vaccinated, including patients with varicose veins or venous thromboembolic disease.
“In the Community of Madrid we are more than six million inhabitants and, approximately, between 200 and 300 deep vein thromboses are diagnosed daily, unrelated to the vaccine. We are not observing more cases due to the AstraZeneca vaccination, at all ”, explains Rial, clinical chief of Vascular Surgery at the HM Torrelodones Hospital. “All drugs have risks. The risk of being vaccinated with AstraZeneca is much lower, for example, than taking aspirin and having digestive bleeding, which can be fatal ”, argues the surgeon.
The first investigations , led by the German hematologist Andreas Greinacher, suggest that the Very rare cases of clots after vaccination could be due to a mechanism similar to that observed with another drug, heparin, which is paradoxically an anticoagulant. Susceptible people, who are a very small percentage, produce an immune response after receiving heparin that can lead to the formation of thrombi.
AstraZeneca's chief medical officer, Ann Taylor, has insisted in recent weeks that the relationship between her vaccine and clots is not proven. The company said on March 18 that its internal analyzes of tens of millions of vaccinated do not show that thrombi are more frequent than expected without the vaccine. The European Medicines Agency will publish this Wednesday a new recommendation on the use of the injection of AstraZeneca.
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