Yes, when the vaccines first came in limited supply, they went out to the most vulnerable. And the doctors of the most vulnerable know the immune system very well. There was absolutely no dose/response guidance from the CDC (there are nefarious reasons for this, but not the subject). The doctors of the first patients did test for antibody responses to compare with the true positive antibody responses -- and found the vaccinated were not producing antibodies. They complained to the CDC and were told to shut up. The CDC issued guidance, that unlike all other vaccines, the magic RNA vaccines are magic and to shut up.