Message : Required fields ZURICH (Reuters) - A German scientist studying extremely rare blood clots linked to AstraZeneca's COVID-19 vaccine said on Tuesday Johnson & Johnson has agreed to work with him on the research after similar serious side effects emerged in recipients of its shot. Andreas Greinacher, a transfusion medicine expert at Greifswald University, announced the collaboration after the European Medicines Agency said it would add a label to J&J's vaccine warning of unusual blood clots with low platelet counts. AstraZeneca's shot has a similar warning. As with AstraZeneca, the EMA said benefits of getting J&J's shot still outweigh the clotting risk, a position Greinacher backs, too.