I'm genuinely curious if you could sue Google if you got J&J because of their mandate and you happened to be one of the extremely rare folks who got a blood clot from it.
Are there vaccines widely available in the US whose delivery mechanism was well established before 2020? The J&J vaccines are viral vector, a class of vaccines which has only been approved for human use twice before, in presumably small numbers. https://en.wikipedia.org/wiki/Viral_vector_vaccine
Not yet. I believe Novavax's protein subunit vaccine would use the same mechanism as the MMR vaccine. Well outside my domain but my understanding is that you're given a premade dose of SARS-CoV-2 spike proteins and an adjuvant to boost an immune rsponse to them, instead of producing the spike proteins yourself (as is the case for both mRNA and viral vector vaccines). [1] gives results of their phase 3 trials. The Atlantic [2] gives an overview aimed at a popular audience.