French Regulator Confirms Rare Thrombosis Risk Linked to AstraZeneca Vaccine

Paris, March 28 (Science and Technology Daily) (Reporter Li Hongce) – On the 26th, the French National Agency for the Safety of Medicines and Health Products (ANSM) confirmed that the AstraZeneca vaccine carries a “rare” risk of causing atypical blood clots. Recently, several cases of thrombotic events have been reported among vaccine recipients in France, including two deaths between March 12 and 18.

According to the latest data from ANSM monitoring, nine people in France developed venous thrombosis between the 12th and 18th after receiving the AstraZeneca vaccine. The locations of these clots were atypical, primarily affecting cerebral veins and the gastrointestinal tract, which may be associated with patients' thrombocytopenia or coagulation disorders. Two of the nine individuals died, including a medical student from Nantes University who had been interning at the university's affiliated hospital. French health authorities are conducting an in-depth clinical investigation into this case.

The ANSM stated that these rare cases of atypical thrombosis shared similar clinical presentations and onset timelines, with a median time to thrombosis onset of 8.5 days following vaccination. The patients had no specific medical history; seven were under 55 years of age, and two were over 55.

Due to concerns over the risk of blood clots associated with the AstraZeneca vaccine, many European countries successively suspended its administration starting March 15. The preliminary findings of an investigation released by the European Medicines Agency on the 18th indicated that the AstraZeneca vaccine is safe and effective, with benefits outweighing the risks of adverse reactions; the vaccine does not increase the overall risk of thrombosis in recipients; there is no evidence linking the reported thrombotic cases to specific batches or production sites of the AstraZeneca vaccine; however, a causal link between these thrombotic cases and the vaccine cannot yet be definitively excluded.

The European Medicines Agency recommended continuing vaccinations, and France lifted its vaccination ban on the 19th. However, the French High Authority for Health (HAS) advised using the vaccine only for individuals aged 55 and older, as previous thrombosis cases were concentrated among those under 55. Previously, healthcare workers under 50 without underlying conditions in France could only receive the AstraZeneca vaccine.

As of March 18, among the 1.4 million doses of AstraZeneca vaccine administered in France, pharmacovigilance centers observed approximately 5,700 adverse reactions, the vast majority of which were severe influenza-like syndromes, including fever, headache, and myalgia.

Currently, the AstraZeneca vaccine has become the most administered vaccine in France on a daily basis. The ANSM emphasizes that the benefits of receiving the AstraZeneca vaccine still outweigh the risks of adverse reactions.