Dr. Richard Kuhn, Purdue University virus expert, notes, “It’s hard to say if it’s the same problem—but it does seem the vaccine triggers an antibody response that activates platelets, leading to clots.” On a final note, as reported by CNBC, J&J had privately asked rivals Moderna and Pfizer to join in a study looking at blood clot risks, but the two firms declined. Per news reports, “Executives at Pfizer and Moderna said their vaccines appeared safe and they didn’t see the need to duplicate the efforts of regulators and companies already looking into the rare blood clot issue.” AstraZeneca did accept the offer to partner on clot research.

Dr. Richard Kuhn, Purdue University virus expert, notes, “It’s hard to say if it’s the same problem—but it does seem the vaccine triggers an antibody response that activates platelets, leading to clots.” On a final note, as reported by CNBC, J&J had privately asked rivals Moderna and Pfizer to join in a study looking at blood clot risks, but the two firms declined. Per news reports, “Executives at Pfizer and Moderna said their vaccines appeared safe and they didn’t see the need to duplicate the efforts of regulators and companies already looking into the rare blood clot issue.” AstraZeneca did accept the offer to partner on clot research.