A Study on the Immune Response and Safety of a Combined Measles, Mumps, Rubella, Chickenpox Vaccine Compared to a Marketed Combined Vaccine, Given to Healthy Children 4 to 6 Years of Age

Inclusion Criteria:

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

• A male or female between, and including, 4 years and 6 years of age (i.e., from 4year birthday until the day before the 7-year birthday) at the time of studyintervention administration, and in accordance with local regulations.

• Participant who previously received a first dose of varicella-containing vaccine inthe second year of life.

• Participant who previously received a single dose of measles-, mumps-,rubella-containing vaccine in the second year of life.

• Written informed consent obtained from the participants' parent(s)/legallyacceptable representative(s) (LAR[s]) prior to performance of any study-specificprocedure (participant informed assent will be obtained from participants in linewith local rules and regulations).

• Participants' parent(s)/LAR(s), who, in the opinion of the investigator, can andwill comply with the requirements of the protocol (e.g., completion of electronicdiaries [eDiaries], return for follow-up visits).

Exclusion Criteria:

Medical Conditions

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

• Any confirmed or suspected immunosuppressive or immunodeficient condition, based onmedical history and physical examination (no laboratory testing required).

• Hypersensitivity to latex.

• Major congenital defects, as assessed by the investigator.

• History of measles, mumps, rubella, or varicella disease.

• Recurrent history of or uncontrolled neurological disorders or seizures.

• Acute disease at the time of enrollment. Acute disease is defined as the presence ofa moderate or severe illness with or without fever. Fever is defined as bodytemperature >=38.0 degrees Celsius (°C) (100.4 degrees Fahrenheit [°F)] by anyage-appropriate route. All study interventions can be administered to participantswith a minor illness such as diarrhea, mild upper respiratory infection withoutfever.

• Participant with history of coronavirus disease 2019 (COVID-19) who is stillsymptomatic.

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

Prior and Concomitant Therapy

• Use of any investigational or non-registered product (drug, vaccine, or medicaldevice) other than the study interventions during the period beginning 30 daysbefore the dose of study interventions (Day -29 to Day 1), or their planned useduring the study period.

• Chronic administration (defined as more than 14 days in total) of immunosuppressantsor other immune-modifying drugs during the period starting 90 days prior to thestudy intervention administration. For corticosteroids, this will mean prednisoneequivalent >= 0.5 mg/kg/day or 20 mg/day whichever is the maximum dose for pediatricparticipants. Inhaled and topical steroids are allowed.

• Administration of immunoglobulins and/or any blood products or plasma derivativesduring the period starting 180 days before the dose of study interventions orplanned administration during the study period.

• Administration of long-acting immune-modifying drugs at any time during the studyperiod (e.g., infliximab).

• Previous vaccination with a second dose of varicella-containing vaccine or measles-,mumps-, rubella-containing vaccine.

• Administration or planned administration of a vaccine not foreseen by the studyprotocol in the period starting 30 days before the dose and ending at 43 days afterthe dose of study interventions administration* (Visit 3), with the exception of:

• inactivated influenza (flu) vaccine which may be given at any time during thestudy and administered at a different location than the study interventionsand,

• routinely recommended licensed childhood DTPa-containing vaccines which canpreferably be co-administered according to the local immunization practices ofthe participating country.

• Any other age-appropriate vaccine may be given starting at Visit 3 and anytimethereafter.

• In case an emergency mass vaccination for an unforeseen public health threat (e.g., a pandemic) is recommended and/or organized by public health authoritiesoutside the routine immunization program, the time period described above canbe reduced if necessary for that vaccine, provided it is used according to thelocal government recommendations and that GSK/IQVIA is notified accordingly.

Prior/Concurrent Clinical Study Experience

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

Other Exclusions

• 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 <28 weeks of gestation.