COVID-19 side effects: What is thrombocytopenia, that’s being linked to the AstraZeneca vaccine?

Naturally occurring thrombocytopenia affects about one in 30,000 adults a year in the United States.

from http://www.firstpost.com/health/covid-19-side-effects-what-is-thrombocytopenia-thats-being-linked-to-the-astrazeneca-vaccine-9522601.html