Comparison of inactivated poliovirus vaccine and oral poliovirus vaccine programs in Israel.

In spite of high vaccination coverage, paralytic poliomyelitis still occurs in Israel, either in sporadic form in the urban area or in small outbreaks in the rural, non-Jewish segment. At high risk are mainly very young infants, not yet protected by poliovirus vaccine and children who have failed to seroconvert after a full course of oral poliovirus vaccine ( OPV ). In these circumstances, a new program for vaccination of young infants early in life with a quadruple vaccine containing inactivated poliovirus vaccine (IPV) and diphtheria, tetanus, and pertussis vaccines (DTP) has been tested. Administration of two doses of IPV up to the age of three and one-half months followed by a booster at the age of 10 months has produced a very satisfactory antibody response (100% seroconversion and high geometric mean titers of antibody to the three antigens), which has occurred early in life and persisted up to two years after booster. This response was similar to that observed after four doses of trivalent OPV ( TOPV ) reinforced with one dose of monovalent type 1 OPV . Two doses of the quadruple vaccine have also induced an antibody response to pertussis antigen in greater than 90% of the infants. After booster, a greater than 99% conversion rate has been recorded, which has remained unchanged at one year of follow-up. The above data have led to the modification of the poliovirus vaccination schedule in the areas at risk.