A Phase 2 Study to Learn About a Monovalent Pneumococcal Conjugate Candidate in Healthy Toddlers

A Phase 2, Randomized, Open-Label Trial to Describe the Safety and Immunogenicity of a Monovalent Pneumococcal Conjugate Candidate Administered As a 2-Dose Series in Healthy Toddlers 11 Through 15 Months of Age Who Previously Received the PCV10 Primary Series

The purpose of the study is to learn about the effects of a monovalent (single component) pneumococcal conjugate candidate (mPnC candidate) when given to toddlers between 11 and 15 months of age.

All participants in this study will receive 2 doses of either mPnC candidate or mPnC control at the clinic approximately 8 weeks apart. All participants will also receive their third (toddler) dose of PCV10 at Visit 1.

Key Inclusion Criteria:

• Toddlers ≥11 to ≤15 months of age at the time of consent.
• Have received exactly 2 infant doses of PCV10 according to a local immunization schedule.
• Healthy toddlers determined by clinical assessment, including medical history and clinical judgment, to be eligible for the study.

Key Exclusion Criteria:

• History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of study intervention, 13vPnC, 20vPnC, or any diphtheria toxoid-containing vaccine.
• significant neurological disorder or history of seizure (excluding febrile seizure) or significant stable or evolving disorders such as cerebral palsy, encephalopathy, hydrocephalus, or other significant disorders.
• Major known congenital malformation or serious chronic disorder.
• History of microbiologically proven invasive disease caused by S pneumoniae.
• Previous vaccination with any licensed pneumococcal vaccine (other than the PCV10 primary infant series) or investigational pneumococcal vaccine, or planned receipt of nonstudy pneumococcal vaccine during study participation.