A Study on the Immune Response and Safety of an Investigational Chickenpox Vaccine When Given to Healthy Children 12 to 15 Months of Age

Inclusion Criteria:

• Participant's parent(s) Legally acceptable representatives /(LAR[s]), who, in theopinion of the investigator, can and will comply with the requirements of theprotocol (e.g., completion of the eDiaries, return for follow-up visits).

• Written or witnessed/thumb printed informed consent obtained from the participant'sparent(s)/LAR(s) prior to performance of any study-specific procedure.

• Healthy participants as established by medical history and clinical examinationbefore entering into the study.

• A male or female between, and including, 12 to 15 months of age (i.e., from the dayof 1-year birthday until the day before 16 months of age) at the time of theadministration of study interventions.

• Only for children in countries where PCV is recommended at 12 to 15 months of age asper national immunization schedule and provided as part of the study interventions:

• Participant who previously received the primary series of PCV in the first yearof life with last dose at least 60 days prior to study entry.

Exclusion Criteria:

• History of any reaction or hypersensitivity likely to be exacerbated by anycomponent of the study interventions.

• Any confirmed or suspected immunosuppressive or immunodeficient condition, based onmedical history and physical examination.

• Hypersensitivity to latex.

• Major congenital defects, as assessed by the investigator.

• Recurrent history of uncontrolled neurological disorders or seizures.

• History of varicella disease.

• Active untreated tuberculosis.

• Any other clinical condition that, in the opinion of the investigator, might poseadditional risk to the participant due to participation in the study.

• Use of any investigational or non-registered product (drug, vaccine or invasivemedical device) other than the study interventions during the period beginning 30days before the dose of study interventions administration (Day -29 to Day 1), ortheir planned use during the study period.

• Planned administration of a vaccine in the period starting 30 days before the doseand ending 43 days after the dose of study interventions administration* (Visit 2)with the exception of inactivated influenza vaccine which may be given at any timeduring the study and administered at a different location than the studyinterventions.

Any other age-appropriate vaccine may be given starting at Visit 2 and anytime thereafter.

*If emergency mass vaccination for an unforeseen public health threat (e.g., a pandemic) is organized by public health authorities outside the routine immunization program, the time period described above can be reduced provided it is used according to the local governmental recommendations and sponsor is notified

• Chronic administration of immune-modifying drugs (defined as more than 14consecutive days in total) and/or planned use of long-acting immune modifyingtreatments at any time up to the end of the study.

• Up to 90 days prior to the study intervention administration:

• For corticosteroids, this will mean prednisone equivalent >=0.5 mg/kg/day withmaximum of 20 mg/day for pediatric participants. Inhaled and topical steroidsare allowed.

• Administration of immunoglobulins and/or any blood products or plasmaderivatives.

• Up to 180 days prior to study interventions administration: long actingimmune-modifying drugs including among others immunotherapy (e.g., tumornecrosis factor-inhibitors), monoclonal antibodies (except the ones notinterfering with the immune response to the study vaccines, e.g., nirsevimab),antitumoral medication.

• Previous vaccination against measles, mumps, and rubella.

• Previous vaccination against hepatitis A virus.

• Previous vaccination against varicella virus.

• Only for children in countries where PCV is recommended at 12 to 15 months of age asper national immunization schedule and provided as part of the study interventions,participant who previously received a booster dose of any PCV.

• Concurrently participating in another clinical study, at any time during the studyperiod, in which the participant has been or will be exposed to an investigationalor a non-investigational intervention (drug/invasive medical device).

• Child in care.

• Any study personnel's immediate dependents, family, or household members.

• Participants with the following high-risk individuals in their household:

• Immunocompromised individuals.

• Pregnant women without documented history of varicella.

• Newborn infants of mothers without documented history of varicella.

• Newborn infants born less than (<) 28 weeks of gestation.