A Study on the Immune Response and Safety of an Investigational Combined Measles, Mumps, Rubella and Varicella Vaccine, When Given to Healthy Children 4 to 6 Years of Age

Inclusion criteria

(INC):

• INC#1 Participant's parent(s)/LAR(s), who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the eDiaries, return for follow-up visits).
• INC#2 Written or witnessed/thumb printed or digital informed consent obtained from the participant's parent(s)/LAR(s) prior to performance of any study specific procedure.
• INC#3 Informed assent obtained from the participants in line with local rules and regulations.
• INC#4 Healthy participants as established by medical history and clinical examination at screening.
• INC#5 A male or female participant between and including 4 and 6 years of age (i.e., from fourth birthday until the day before the seventh birthday) at the time of the study interventions administration, and in accordance with local regulations.
• INC#6 Participant who previously received a first dose of varicella-containing vaccine in the second year of life (i.e., from first birthday at 12 months of age until the day before the second birthday at 24 months of age).
• INC#7 Participant who previously received a first dose of measles, mumps, rubella containing vaccine in the second year of life (i.e., from first birthday at 12 months of age until the day before the second birthday at 24 months of age).
• INC#8 Participant who previously received 3 or 4 doses of any combined DTP (DTaP/DTwP) vaccine (diphtheria and tetanus toxoids and pertussis antigens whether or not combined with hepatitis B, inactivated poliovirus or Haemophilus influenzae type b antigens) according to the local recommendations.

Exclusion criteria

(EXC):

• EXC#1 History of any reaction or hypersensitivity likely to be exacerbated by any component of the study interventions, including hypersensitivity to neomycin or gelatin.
• EXC#2 Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required).
• EXC#3 Hypersensitivity to latex.
• EXC#4 Unstable chronic conditions as determined by medical history and physical examination.
• EXC#5 Major congenital defects, as assessed by the investigator.
• EXC#6 History of measles, mumps, rubella or varicella/zoster disease as evaluated by the investigator.
• EXC#7 History of diphtheria, tetanus, pertussis, and/or poliomyelitis disease.
• EXC#8 Recurrent history or uncontrolled neurological disorders or any neuroinflammatory (including, but not limited to: demyelinating disorders, encephalitis or myelitis of any origin), congenital neurological conditions, encephalopathies, or seizures (including all subtypes, such as: absence seizures, generalized tonic-clonic seizures, partial complex seizures, partial simple seizures).
• EXC#9 Active untreated tuberculosis.
• EXC#10 Condition that, in the judgment of the investigator, would make intramuscular injection unsafe.
• EXC#11 Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the clinical study.
• EXC#12 Use of any investigational or non-registered product (drug, vaccine, or invasive medical device in the country of enrollment) other than the study interventions during the period beginning 30 days before the dose of study interventions (Day -29 to Day 1), or their planned use during the study period.
• EXC#13 Administration of immunoglobulins or other blood products or plasma derivatives during the period starting 90 days before the study intervention or planned administration during the study period.
• EXC#14 Chronic administration of immune-modifying drugs (defined as more than 14 consecutive days in total) and/or planned use of long-acting immune modifying treatments at any time up to the end of the study.

• Up to 90 days prior to the study interventions administration.

• For corticosteroids, this will mean prednisone equivalent ≥0.5 mg/kg/day with maximum of 20 mg/day for pediatric participants. Inhaled, intra-articular/intra-bursal and topical steroids are allowed.
• Up to 180 days prior to study interventions administration: long-acting immune-modifying drugs including among others immunotherapy (e.g., tumor necrosis factor-inhibitors), monoclonal antibodies (except the ones not interfering with the immune response to the study interventions, e.g., nirsevimab), antitumoral medication.
• EXC#15 Previous vaccination with a second dose of varicella-containing vaccine or measles, mumps, rubella containing vaccine.
• EXC#16 Vaccination against diphtheria, tetanus, pertussis, and/or poliomyelitis given after the second year of life (i.e., after the second birthday at 24 months of age).
• EXC#17 Occurrence of any of the following events after a previous administration of DTP vaccine:

• Encephalopathy of unknown etiology occurring during the period starting within 7 days of vaccination of a previous administration of DTP vaccine.
• A temperature (≥40.6°C [≥105°F]) during the period starting 48 hours after vaccination not due to another identifiable cause.
• EXC#18 Use of salicylates (aspirin) or salicylate-containing products or its planned use, during the period of 6 weeks following study interventions administration.
• EXC#19 Planned administration/administration of a vaccine not foreseen by the study protocol in the period starting 30 days before the dose and ending 43 days after the dose of study interventions administration* (Visit 2), with the exception of

Influenza vaccines:

• Inactivated influenza vaccine must not be administered in the period starting 28 days before the dose and ending 28 days after the dose of study intervention administration. If administered outside this prohibited period, it should be administered at a different location than the study intervention.
• Live attenuated influenza vaccine must not be administered during the period starting 30 days before the dose and ending 43 days after the dose of study intervention administration (Visit 2).

• If emergency mass vaccination for an unforeseen public health threat (e.g., a pandemic) is recommended and/or 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.

• EXC#20 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/vaccine/invasive medical device).
• EXC#21 Any study personnel's immediate dependents, family, or household members.
• EXC#22 Child in care.
• EXC#23 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.