Study to Evaluate Antibody Persistence in Children Previously Vaccinated With Infanrix Hexa™ or Infanrix-IPV/Hib™

Inclusion Criteria: * Subjects who had received 3 doses of Infanrix hexa™ or Infanrix-IPV/Hib™ in study NCT00307034. * Subjects who the investigator believes that parent(s)/Legally Acceptable Representative(s) LAR(s) can and will comply with the requirements of the protocol. * A male or female subject aged 5 years at the time of study entry. * Written informed consent obtained from the parent(s)/LAR(s) of the subject. * Healthy subjects as established by medical history and clinical examination before entering into the study. Exclusion Criteria: * Child in care. * Concurrently participating in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product. * Use of any investigational or non-registered product within 30 days prior to blood sampling. * Evidence of previous or intercurrent diphtheria, tetanus, pertussis, polio, hepatitis B, and Hib vaccination or disease since the study NCT00307034, with the exception of hepatitis B vaccination in the DTPa-IPV/Hib group. * Administration of immunoglobulins and/or any blood products within the 3 months prior to blood sampling. * Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination. * Family history of congenital or hereditary immunodeficiency.