International 07/04/2021

EMA concludes that thrombi may be a side effect of AstraZeneca in very rare cases

Regulator, however, reiterates that drug is safe because benefits outweigh risks

2 min
The Director of the European Medicines Agency, Emer Cooke.
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BrusselsAstraZeneca's vaccine can cause thrombosis as a "very rare" side effect. After weeks of ups and downs, contradictory information and policies on the alleged link between the doses developed by Oxford University and some cases of thrombosis detected in different countries, this is the conclusion of the European Medicines Agency (EMA), which has given another press conference after one of its experts said in an interview with Italian newspaper Il Messaggero that there is a link between AstraZeneca's coronavirus vaccine and cases of thrombosis. Even so, the regulator continues to strongly defend the use of this drug.

"Coronavirus is a very serious disease and we have to use all the vaccines we have," Cooke said. In its statement, the EMA insists that covid-19 carries a high risk of hospitalisation and death while cases of thrombosis are "very rare". Therefore, it insists that the "overall benefits of this vaccine outweigh the risks of side effects"

Thus, the EMA recommends continuing to administer this vaccine but also recommends health professionals and people receiving the vaccine to "be aware of the possibility of very rare cases of blood clots combined with low blood platelet levels during the two weeks following vaccination".

The EMA's conclusion comes after studying cases up to 22 March, when 25 million people had been vaccinated with AstraZeneca in the European Union and the United Kingdom. There are 62 cases of cerebral venous thrombosis and 24 cases of other thrombosis. Of these, 18 were fatal. Most, says the regulator, are women under 60 who had received the vaccine two weeks earlier, but it concludes that there is still insufficient evidence on specific risk factors such as gender and age.

In the first half of March, some 20 European countries abruptly suspended the vaccination campaign with the Anglo-Swedish pharmaceutical company's vials after governments of Germany and Norway among others detected up to 30 cases of serious thrombosis in people who had been vaccinated. After the alarm raised by this situation, the EMA appeared urgently to defend the "safety and efficacy" of the vaccine. At the time, Cooke made it clear that the regulator's job was to continue to monitor the application of the vaccine, both AstraZeneca's and any of the other coronavirus vaccines that have been approved through an accelerated process.

The EMA has always reiterated that the benefits of the drug outweigh the risks because the number of cases of thrombosis detected so far are a tiny percentage of the total number of people vaccinated. In fact, 25 million people have been vaccinated with these doses and there are only a few dozen severe cases of thrombosis. Even so, the regulator put to work a team of experts such as hematologists, neurologists and epidemiologists who have been studying the data over the past few days.

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