This page has a list of countries by Immunization, Hib3 (% of children ages 12-23 months), according to officially-recognized international sources compiled by the World Bank. Child immunization, Hib3, measures the percentage of children ages 12-23 months who received Hib3 vaccinations before 12 months or at any time before the survey. A child is considered adequately immunized against Hib3 after receiving three doses of Haemophilus influenzae type b vaccine.