Clinical Research Directory

Inclusion Criteria: 1. Participant has an LAR who understands study procedures, alternative treatments and risks involved in the study and who voluntarily agrees to participate by giving informed consent. 2. Participant is a full-term (≥37 weeks gestation at birth) infant approximately 2 months of age (42 to 90 days, inclusive) at time of obtaining the informed consent. 3. Participant is healthy based on the clinical judgment of the investigator following review of medical history and physical examination. Exclusion Criteria: 1. Participant had prior administration of any pneumococcal vaccine. 2. Participant has a known or suspected hypersensitivity to AFX3772, PCV13, PCV20 or any components of the formulations used. 3. Participant has a known or suspected immunodeficiency (including autoimmune disease) or other conditions associated with immunosuppression that may require immunosuppressive drugs including but not limited to HIV infection, malignancy or organ or bone marrow transplant. a. In addition, the participant's biological mother has known HIV infection or known to be hepatitis B surface antigen positive. 4. Participant has any clinically significant allergic condition or history (including anaphylactic reactions, but excluding untreated, asymptomatic, seasonal allergies) prior to the first vaccination for primary immunization series. 5. Participant has functional asplenia. 6. Participant has medical history of epilepsy or febrile convulsion. 7. Participant weighed \<2000 g at birth. 8. Participant has known neurological or cognitive behavioral disorders including clinically significant developmental disorder and related disorders. 9. Participant has any active malignancy or history of malignancy. 10. Participant has a history of microbiologically proven invasive disease caused by S. pneumoniae. 11. Participant has cochlear implant or cerebrospinal fluid leakage. 12. Has received other licensed non-live vaccines within the 14 days or a licensed live virus vaccine within the 30 days prior to receipt of study vaccine. 13. Participant has received immunoglobulins. Note: This does not include monoclonal antibodies, such as palivizumab or nirsevimab. 14. Participant has a bleeding diathesis or condition associated with prolonged bleeding that would contraindicate intramuscular injection. 15. Participant has received systemic corticosteroids (equivalent of \>2 mg/kg total daily dose of prednisone or \>20 mg/day for persons weighing \>10 kg) for a period of more than 14 days and has not completed the treatment for at least 30 days before study vaccine. Topical, ophthalmic, and inhaled steroids are allowed. 16. Participant has febrile illness (rectal temperature ≥38.1°C \[100.5°F\] or axillary temperature ≥37.8°C \[100.0°F\]) in Part 1 and Part 2 prior to the effective date of protocol amendment 4. After protocol amendment 4 becomes effective, febrile illness is defined as rectal temperature ≥38.0°C \[100.4°F\] or axillary temperature ≥37.5°C (99.1°F) in Part 2. Upon resolution of symptoms, participant can be rescreened. 17. Participant has received any investigational therapy within 28 days or 5 half-lives, whichever is longer, prior to screening. 18. Participant has any condition which, in the investigator's opinion, makes the participant unsuitable for study participation. 19. LARs that are study personnel or their immediate dependents, family, or household members.