The mechanism of action of the Johnson & Johnson and AstraZeneca vaccines is DNA, which is effectively like mRNA but with a couple of extra steps with their own risk attached. I think there's some suspicion that the blood clotting issues with the AZ vaccine were due to errors in the DNA to mRNA transcription causing erroneous and dangerous proteins to be produced. There's not really any traditional inactivated vaccines in widespread use against Covid at the moment.