http://www.sciencemag.org/news/2021/04/do-preservative-and-stray-proteins-cause-rare-covid-19-vaccine-side-effect

The European Medicines Agency paved the way this week for Europe’s use of a COVID-19 vaccine made by Johnson & Johnson, but questions persist about a rare clotting side effect linked to it and a similar vaccine made by AstraZeneca.

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