I have a tentative answer! Some cursory googling makes me think that J&J also just replicates the spike protein in you, the same way Pfizer/Moderna do. This means it’s just strictly less effective. Then you’d want to just do the Pfizer/Moderna one that you haven’t yet—unless Elizabeth’s comment about limited mRNA vaccine doses is decision-relevant, which I still haven’t looked into.
I have a tentative answer! Some cursory googling makes me think that J&J also just replicates the spike protein in you, the same way Pfizer/Moderna do. This means it’s just strictly less effective. Then you’d want to just do the Pfizer/Moderna one that you haven’t yet—unless Elizabeth’s comment about limited mRNA vaccine doses is decision-relevant, which I still haven’t looked into.