A Phase 2 Study to Evaluate the Safety, Tolerability, and Immune Response of AFX3772 Vaccine in Healthy Infants

Inclusion Criteria: • Is a full-term infant approximately 2 months of age at time of obtaining the informed consent. Exclusion Criteria: * Had prior administration of any pneumococcal vaccine. * Has a known or suspected hypersensitivity to AFX3772, PCV13, PCV20 or any components of the formulations used. * Has a known or suspected immunodeficiency or other conditions associated with immunosuppression that may require immunosuppressive drugs. In addition, the participant's biological mother has known HIV infection or known to be hepatitis B surface antigen positive. * Has any clinically significant allergic condition or history prior to the first vaccination for primary immunization series. * Has a history of microbiologically proven invasive disease caused by S. pneumoniae. * Has received immunoglobulins. * Has a bleeding diathesis or condition associated with prolonged bleeding that would contraindicate intramuscular injection. * Has received systemic corticosteroids for a period of more than 14 days and has not completed the treatment for at least 30 days before study vaccine.