EFFECTIVENESS OF A NATIONWIDE INFANT IMMUNIZATION PROGRAM AGAINST HAEMOPHILUS-INFLUENZAE-B

An ongoing nationwide prospective surveillance program for invasive H. influenzae b (Hib) disease in Israel enabled us to study the effectiv eness of a national infant Hib immunization program, which included al l infants born since January 1994. The vaccine used was Hib polysaccha ride conjugated to outer membrane protein complex of Neisseria meningi tidis b (PRP-OMPC). For the cohort born during the 3 years since Janua ry 1994, the vaccine effectiveness was 94.9% for all invasive Hib dise ases and 96.6% for meningitis. The efficacy in fully immunized subject s was 98.7 and 99.5%, respectively. A herd immunity effect could be ob served, since a reduction in cases also occurred among infants too you ng to be immunized. No increase in invasive cases caused by S. pneumon iae and N. meningitidis was observed during the study period. This is the first report outside North America and Western Europe that demonst rates a nationwide extensive reduction of invasive Hib disease within a short time of the introduction of Hib conjugate vaccines to the infa nt immunization program. (C) 1998 Published by Elsevier Science Ltd. A ll rights reserved.