A new study hints at a reason the J.&J. and AstraZeneca vaccines may cause blood clots in rare cases.

A panel of experts advising the Centers for Disease Control and Prevention is discussing rare blood clots that health officials have investigated in Johnson & Johnson coronavirus vaccine recipients.

source https://www.nytimes.com/2021/04/23/health/astrazeneca-johnson-covid-vaccine-blood-clots.html