EFFECT OF MATERNAL IMMUNIZATION WITH ORAL POLIOVIRUS VACCINE ON NEONATAL IMMUNITY

During the summer of 1988, an outbreak of poliomyelitis caused by poli ovirus 1 occurred in Israel, during which a national mass immunization campaign with oral poliovirus was undertaken. This prospective study was undertaken to assess the effect of maternal oral poliovirus immuni zation during the third trimester of pregnancy on neonatal immunity ag ainst poliovirus. Cord blood specimens of 88 neonates, born 2 to 7 wee ks after maternal immunization, were examined for antipoliovirus antib odies and compared with 100 samples obtained from neonates 7 months be fore the outbreak. Blood samples were also obtained from the 62 mother s of neonates who had been immunized 2 to 5 weeks before delivery. Ser a were tested for neutralizing antibodies to the 3 poliovirus types us ing a microneutralization technique. The geometric mean titer to polio virus type 1 was significantly higher in neonates whose mothers were i mmunized during pregnancy (87.1) than in the offspring of the nonvacci nated group (53.0), P < 0.05. Two to 3 weeks after immunization, geome tric mean titers against all 3 poliovirus types were higher in materna l blood than in cord blood whereas 4 to 5 weeks after vaccination a si gnificant difference was found for type 3 only. Although oral poliovir us immunization during pregnancy resulted in higher neonatal antibody titers to poliovirus type 1, the proportion of newborns with titers of < 1:8 to the 3 poliovirus types did not change significantly.