http://www.sciencemag.org/news/2021/04/hard-choices-emerge-link-between-astrazeneca-vaccine-and-rare-clotting-disorder-becomes

Science’s COVID-19 reporting is supported by the Heising-Simons Foundation.

What was a worrisome suspicion four weeks ago is now widely accepted: The AstraZeneca COVID-19 vaccine can, in very rare cases, cause a disorder characterized by dangerous blood clots and low platelet counts. In Europe, at least 222 suspected cases have been reported among 34 million who have received their first dose of the vaccine. More than 30 have died.