"A possible link exists between very rare cases of unusual blood clots with low blood platelets and the Janssen (Johnson & Johnson) covid-19 vaccine, but the benefits still outweigh the risks, the European Medicines Agency (EMA) has said.
The EMA’s Pharmacovigilance Risk Assessment Committee has reviewed all available evidence including eight cases reported in the US, one of which had a fatal outcome. As of 13 April 2021 over seven million people had received Janssen’s one dose vaccine in the US. A warning about the clots will be added to the product information, describing them as a 'very rare side effect.' ...
Janssen announced that on 13 April it had 'proactively delayed' the rollout of its vaccine in Europe, which was due to start that week. US regulators have also paused rollout, and their investigations are ongoing. When asked why the EMA came to a decision before the US did, Emer Cooke, the agency’s executive director, said that it had experience of looking at this issue because of its previous AstraZeneca investigations.
For both vaccines, the EMA has said that a plausible explanation for the unusual combination of blood clots and low blood platelets is an immune response leading to a condition similar to one seen sometimes in patients treated with heparin, called heparin induced thrombocytopenia."
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