J&J recognizes thrombosis as a side effect

The European Medicines Agency has recommended that thrombosis
be listed as a side effect of a vaccine from Johnson & Johnson called
Janssen. This was reported by the official press service of the agency
and the Reuters agency. In particular, it reported that the PRAC had
concluded that there was a link between Johnson & Johnson's COVID
vaccine and cases of venous thromboembolism, i.e. the formation of
blood clots in deep veins. It is also recommended to add immune
thrombocytopenia to the side effects - a condition when, due to a
failure, the immune system begins to fight its own platelets. 
The latter problem is common not only for Johnson & Johnson, but
also for the AstraZeneca vaccine. The reasons for these side effects
remain unknown.