AstraZeneca about investigating the clots and to “speak with one voice about safety.” However, both Pfizer and Modera declined, indicating that their vaccines were not associated with blood clots.
The two companies didn’t see a need to duplicate regulators investigations, and they are already studying the blood clotting. Some of the sources said there were concerns Pfizer and Moderna might be linked to the blood clotting issue.
So far, both the AstraZeneca-Oxford and Johnson & Johnson COVID-19 vaccines have been
associated with very rare but potentially life-threatening blood clots. The actual cause of the clotting has not been determined.
In addition, the blood associated with each vaccine appears to be different from the other. The U.S. has paused the distribution of the J&J vaccine. The AstraZeneca-Oxford vaccine has been halted in about 20 European countries but has yet to be authorized in the U.S.