Immunogenicity and Safety Study of Proquad® and Infanrix® Hexa When Administered Concomitantly (V221-035)

Inclusion Criteria: * Healthy participants of either gender * Aged 12 to 23 months * No clinical history of measles, mumps, rubella, varicella and zoster * For Italy: Primary vaccination with the combined diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis and Haemophilus influenzae type b vaccine Infanrix® hexa as a 2-dose schedule, with receipt of the second dose ≥ 6 months prior to inclusion * For Germany: Primary vaccination with the combined diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis and Haemophilus influenzae type b vaccine Infanrix® hexa as a 3-dose schedule, with receipt of the third dose ≥ 6 months prior to inclusion * Consent form signed by parent(s) according to local regulations or by the legal representative properly informed about the study * Parent(s)/legal representative able to understand the protocol requirements and to fill in the Diary Card. Exclusion Criteria: * Prior receipt of measles, mumps, rubella and/or varicella vaccine either alone or in any combination * Any recent (\<= 30 days) exposure to measles, mumps, rubella, varicella and/or zoster * Receipt of any other diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis and/or Haemophilus influenzae type b containing vaccine (either alone or in any combination) than Infanrix® hexa * Any recent (\<= 3 days) history of febrile illness * Any severe chronic disease * Active untreated tuberculosis * Known personal history of encephalopathy, seizure disorder or progressive, evo…