Why does the vaccine pose a risk of thrombosis?
The Pharmacovigilance Committee (PRAC) of the European Medicines Agency has concluded that the AstraZeneca vaccine is linked to certain types of thrombosis and blood clot formation. But where does this link come from? “We don’t know for now, admitted this Thursday morning the epidemiologist Yves Van Laethem, at the microphone of La Première. Is it related to the way in which this famous S protein is expressed in the context of this vaccine? Is it linked to the very principle of the vaccine? These data will be important, so as to see the possible impact in the future on other types of vaccination.“
Why limit it to people over 56?
The risk of developing thrombosis is very low in the elderly, especially after 56 years. This is what motivated this decision: Yves Van Laethem considers that it is above all a question of “reallocating” the AstraZeneca vaccine, which is not really stopped. “IThe vaccine must be reallocated to people for whom there is not this rare side effect that has been demonstrated and this switch simply allows practically no time to be wasted“, specifies the epidemiologist.
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This pivotal age is also recommended in other countries: Canada and France, for example, also decided in March to reserve the AstraZeneca vaccine for over 55s. “About 85 to 90% of side effects happen before the age of 55“, notes Yves Van Laethem. Especially since after this age, the risk of dying from Covid-19 increases sharply.”At this point, the benefit of vaccination far outweighs the potential risk in this age group, over 55 years of age.“, concludes the epidemiologist.
Why is the age not the same everywhere in Europe?
Other European countries have chosen different ages: 60 years in Spain and Italy for example, or even only 30 years for Great Britain. Yves Van Laethem regrets a lack of European consensus: “We had already felt it, since before this decision by the European Medicines Agency, there were already decisions in various directions.“
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However, this difference in strategy is also explained by the different situations with regard to vaccination. “Some countries have a campaign that is very focused on AstraZeneca, this is the case among others in Great Britain, which depends a lot on it, recalls the epidemiologist. It is clear that for them the choice is difficult. They must admit a little more risk of side effects to continue their campaign.“
Will this slow down the vaccination campaign?
According to Yves Van Laethem, there is no need to worry about the continuation of the vaccination campaign. “Thanks to the arrival of different vaccines, the massive arrival of Pfizer vaccines among others and the imminent arrival of other vaccines such as Johnson & Johnson, we were able to rearrange the campaign so that the impact was extremely limited“, he explained this Thursday morning on La Première. According to him, it will be”of the order, probably at the end of the campaign, of one to two weeks for the other vaccines which must arrive“.
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Same story with the federal health ministers Franck Vandenbroucke (sp.a) and in Brussels Alain Maron (Ecolo): there will be no major upheaval. For Frank Vandenbroucke, the Belgian health ministers actually followed the opinion of the Superior Health Council on Wednesday: “When you only have AstraZeneca to vaccinate, then you should not hesitate, and use it. But if we have the choice between several vaccines and it does not change the speed of the campaign, then we can adapt“.
In Flanders, we are talking about 6,000 rescheduled vaccinations out of a total of one million, and a few hundred people in Wallonia. In Brussels, these are mainly people over 64 years old.
Will people under 55 who have already received a dose of AstraZeneca be able to have a second dose?
This is a question that also concerns the Belgian ministers of health, who have asked for more clarity from the European Medicines Agency on the best time to administer a second dose or the possibility of using another vaccine. after a first dose of AZ. On Wednesday, the Agency felt that it could not provide an answer on this subject, in particular because too few of these second doses were administered.
He did not rule out the use of another vaccine, but a strategy will be developed by mid-May, when these second doses will have to be administered. It is also not certain that the risk of thrombosis is always present for a second administration.
How long will this restriction last?
The decision to only administer the AstraZeneca vaccine to those over 56 years old will last for four weeks. “It’s a precaution by telling yourself that you will review the situation after a few weeks, explains Yves Van Laethem. We also hope, at that time, to have additional data, and among other things concerning the second dose of vaccine.“In particular, it will be necessary to know if the side effects dissipate during the second dose, as some studies suggest. If the limitation were to last beyond four weeks, the campaign will have to slow down, however, Yvon Englert recalled.
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Anyway, Yves Van Laethem recalls that this is a logical step. “From the moment the risk of the disease is extremely high, an extremely low risk … it’s ultimately the same as taking a car, he says. We all know that when we take our car, we have a risk, but there are circumstances where we still have to take our car.“
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