LIVE POLIO IRUS VACCINES

278
Efficacy-Laboratory Evidence
squirted the strain of virus, suspended in one
cubic centimeter of phosphate-buffered saline
solution, into an ounce of milk in the infant's
bottle or into a cup of chocolate milk.
Serologic Sampling. Twenty-eight per cent of
the children were bled at random before vaccination
so that a significant sample (about 20 per
cent) of paired sera would be obtained (Table
1). Neutralizing antibody titers were determined
in paired pre- and post-vaccination sera from the
same child by the metabolic inhibition test. 9
Serologic Findings Before Vaccination. In the
group one and one-half to three months old only
17 per cent of the sera were without any detectable
antibodies (titers