Immunization with Live Attenuated Poliovirus Vaccine

Live attenuated poliovirus vaccine was administered to 400 newborn infants during a three-month period (October, 1959, to January, 1960). This study was designed to obtain information which might provide answers to the following questions. Would the ingestion of larger doses permit enough of the vaccine viruses regularly to pass the "acid barrier" of the stomach of newborn infants and result in regular multiplication in the intestinal tract? (Poliovirus may be destroyed below a pH of 2.5 and the gastric contents of newborns often have a pH of about 1.5.)1-3 Would it be possible to by-pass the potential handicap of high gastric acidity by swabbing the vaccine directly on the posterior pharyngeal wall? Would all three types multiply following administration of a mixture of large doses of Types 1, 2, and 3 poliovirus either by mouth or by throat as determined by virus excretion and antibody formation? Materials