Hi, from what I know, blood clots (i.e., vaccine-induced thrombotic thrombocytopenia, VITT) are the major concern with DNA-based vaccines that use adenovirus as a carrier.

The mRNA cases are not known to cause blood clots. Although cases of post-mRNA vaccine thrombocytopenia (low platelets) have been documented, scientists believe this is coincidental since the rate of post-mRNA vaccine thrombocytopenia is the same in the unvaccinated population.

VITT is thought to be caused by unwanted interactions between the adenovirus/DNA with platelets, resulting in excessive production of PF4 antibodies that cause blood clots. As far as I know, no other vaccine technology (i.e., Novavax protein-based or inactivated-based vaccines) can do this.

I hope that helps but let me know if anything is unclear.