In the meantime, young Jack Hager had been vaccinated with the Sabin polio vaccine, a live virus that doctors began using in the early '60s in place of the Salk vaccine, made from killed virus.
(young Jack Hager; had been vaccinated; with the Sabin polio vaccine; T:In the meantime) (the Salk vaccine; made; from killed virus)
young Jack Hager the Salk vaccine
had been vaccinated made
with the Sabin polio vaccine T:In the meantime
from killed virus