[tome]

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

[thisiscorrect]

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.

[1] https://www.nejm.org/doi/full/10.1056/NEJMoa2107659 [2] https://www.theatlantic.com/health/archive/2021/06/novavax-n...