Levels of Haemophilus influenzae type B (Hib) antibody in Turkey before routine immunization

Aim: The Haemophilus influenzae type b (Hib) vaccine was introduced into the routine immunization schedule in Turkey on January 1, 2007. This study investigates the immunity to Hib prior to the introduction of the vaccine.Materials and methods: Serum samples were collected from healthy volunteers between the ages of 6 months and 50 +years of age, living in the area of 26 health centers in the Samsun, Antalya, and Diyarbakir provinces during 2000-2001.In total, 1713 sera were selected for this study, and the younger age groups were given priority (range 0-82). A commercial ELISA test was used to measure anti-Hib IgG. Hib antibody concentrations of = 0.15, 0.15 to 1.0, and = 1.0 µg/mLwere considered as non protective, short-term protection, and long term protection, respectively. The statistical analyses performed were the chi-square test and logistic regression. Results: The antibody levels considered non-protective were 58.0%, 35.3%, 28.1%, 19.8%, 18.4%, 15.3%, and 20.6% among 5, 5-9, 10-19, 20-29, 30-39, 40-49, and 50 and over age groups, respectively. Protection against Hib infection increased by age in all 3 provinces. Conclusion: This study provides important baseline data on anti-Hib antibody levels in Turkey before routine immunization was introduced, and shows that there is a considerable percentage of subjects with non-protective antibody levels.