Antibody Persistence, Immune Response and Safety After Doses of Pentabio Vaccine

Inclusion Criteria: * Children, 18-24 months of age * Subjects who had completed the primary series of Pentabio vaccine in the previous trial * Father, mother, or legally acceptable representative have been informed properly regarding the study and signed the informed consent form * Subject's parents commit to comply with the instruction Exclusion Criteria: * Subjects concomitantly enrolled or scheduled to be enrolled in another trial * Evolving mild, moderate or severe illness, especially infectious diseases or fever (axillary temperature \>=37.5oC on Day 0) * Known history of uncontrolled coagulopathy or blood disorders contraindicating intramuscular injection * Known history of allergy to any component of the vaccines (e.f. formaldehyde) * Known history of acquired immunodeficiency (including HIV infection) * Subject who has received a treatment likely to alter immune response in the previous 4 weeks (e.g intravenous immunoglobulin, blood-derived products or long term corticotherapy (\>2 weeks) * Subject receives other vaccination within 1 month prior to inclusion * Any abnormality or chronic disease justified by investigator that might interfere assessment of the trial objectives * Infant with a known history of diphtheria, tetanus, pertussis, Hepatitis B and Hib infection