It appears there are a few different approaches, described here: https://en.wikipedia.org/wiki/RNA_vaccine#Delivery https://en.wikipedia.org/wiki/RNA_vaccine#D

It appears there are a few different approaches, described here: https://en.wikipedia.org/wiki/RNA_vaccine#Delivery https://en.wikipedia.org/wiki/RNA_vaccine#Delivery Viral vectors were the ones I was familiar with. I am not sure which one the Pfizer vax uses, however.