A Clinical Study to Evaluate the Safety, Tolerability, and Immunogenicity of VAX-31 in Healthy Infants

Inclusion Criteria:

1. Healthy male or female infant ≥42 days to ≤89 days.

2. Full-term infant at least 37 weeks gestational age at birth.

3. Afebrile for ≥72 hours with an tympanic or rectal temperature <38.0°C (<100.4°F)before receipt of study vaccine.*Criterion applies to each vaccination. If not met,visit may be rescheduled for a time when no longer febrile for ≥72 hours.

4. Able to attend all scheduled visits and comply with the study procedures.

5. Subject's parent/legal guardian is able to read and understands the studyprocedures, alternate treatments, risks and benefits, and provides written informedconsent.

6. Subject's parent/legal guardian is able to fill out an eDiary of solicited AE andtake daily tympanic temperature and measurements of local injection site reactionsfor the 7 days after each study vaccination.

7. Subject's parent/legal guardian has an email address and access to a computer orsmartphone with internet to complete the eDiary.

Exclusion Criteria:

1. History of invasive pneumococcal disease (positive blood culture, positivecerebrospinal fluid culture, or other sterile site) or known history of otherculture positive pneumococcal disease.

2. Previous receipt of a licensed or investigational vaccine (excluding 1 dose ofhepatitis B vaccine).

3. Known hypersensitivity to any vaccine.

4. Known or suspected impairment of immunological function (e.g., asplenia, humanimmunodeficiency virus, primary immunodeficiency).

5. Use of any immunosuppressive therapy or planned use through the last blood draw (Visit 6). Receipt of a <14-day course of systemic corticosteroids is notexclusionary if completed ≥1 month prior to first study vaccination. Topical andinhaled/nebulized steroids are also permitted.

6. History of failure to thrive or prior hospitalization for any chronic condition.

7. Subject has a bleeding disorder contraindicating IM vaccination.

8. Subject or his/her mother has documented hepatitis B surface antigen-positive test.

9. Subject has a known neurologic or cognitive behavioral disorder.

10. Subject has a known clinically significant congenital malformation or seriouschronic disorder.

11. Receipt of a blood transfusion or blood products, including immunoglobulins.

12. Receipt of any investigational study product since birth, currently participating inanother interventional investigational study, or plans to receive anotherinvestigational product while on study.

13. Any infant who cannot be adequately followed for safety according to the protocolplan.

14. Any other reason that in the opinion of the Investigator may interfere with theevaluation required by the study.