I worked in classified government work and girlfriend works in BioChem. Both of us are heavily against COVID vax because of their unstable and experimental nature. We told the (future) Mother in Law to not take the vax for months and for multiple occasions.
Unfortunatley she took the vax anyway. She's now in critical care for brain aneurysm.
Don't take this vax. Don't bet your life on it.
I'm a little fuzzy but if I remember correctly the pfizer person said something about the vaccine ingredients having a slow release coating. I could be wrong, but that was my take-away.
So I guess if you know how long the slow release takes, you could make that prediction.