Safety, Tolerability, and Immunogenicity of a 24-Valent Pneumococcal Conjugate Vaccine (VAX-24) in Healthy Infants
About the study
The objective of the study is to evaluate the safety and tolerability of 4 injections of VAX-24 (at 3 dose levels) compared to PCV15 in infants at 2, 4, 6, and 12-15 months of age, in addition to receiving routine US concomitant vaccines. Stage 1 of the study will comprise 3 dose ascending cohorts. Stage 2 of the study will enroll the remainder of the sample size.
Who can take part
You may be eligible to participate in the study if you meet the following criteria:
INCLUSION CRITERIA
Inclusion Criteria:
- Healthy male or female infant ≥42 days to ≤89 days (inclusive).
- Full-term infant at least 37 weeks gestational age at birth.
- Afebrile for ≥72 hours with a rectal temperature <38.0°C (<100.4°F) or axillary temperature <37.8°C (<100.0°F) before receipt of study vaccine.*
- Able to attend all scheduled visits and comply with the study procedures.
- Subject's parent/legal guardian is able to read and understands the study procedures, alternate treatments, risks and benefits, and provides written informed consent.
- Subject's parent/legal guardian is able to fill out an ediary of solicited AE and take daily axillary temperature and measurements of local injection site reactions for the 7 days after each study vaccination.
- Subject's parent/legal guardian has an e-mail address and access to a computer or smartphone with internet to complete the ediary.
EXCLUSION CRITERIA
Exclusion Criteria:
- History of invasive pneumococcal disease (positive blood culture, positive cerebrospinal fluid culture, or other sterile site) or known history of other culture positive pneumococcal disease.
- Previous receipt of a licensed or investigational vaccine (excluding 1 dose hepatitis B vaccine).
- Known hypersensitivity to any vaccine.
- Known or suspected impairment of immunological function (e.g., asplenia, HIV, primary immunodeficiency).
- Use of any immunosuppressive therapy (Note: topical and inhaled/nebulized steroids are permitted).
- History of failure to thrive.
- Subject has a coagulation disorder contraindicating IM vaccination.
- Subject or his/her mother have documented hepatitis B surface antigen-positive.
- Has a known neurologic or cognitive behavioral disorder.
- Has a known clinically significant congenital malformation or serious chronic disorder.
- Receipt of a blood transfusion or blood products, including immunoglobulins.
- Receipt of any investigational study product since birth, currently participating in another interventional investigational study, or having plans to receive another investigational product(s) while on study.
- Any infant who cannot be adequately followed for safety according to the protocol plan.
- Any other reason that in the opinion of the investigator may interfere with the evaluation required by the study.

Study Locations
Enter your ZIP code/Postal code/PIN code to locate study sites near you:
How to Apply
Contact the study center to learn if this study is a good match for you.
Study’s details
Contition
Pneumococcal Vaccines
Age (in years)
42 - 89
Phase
PHASE2
Participants needed
802
Est. Completion Date
Dec 31, 2025
Treatment type
INTERVENTIONAL
Sponsor
Vaxcyte, Inc.
ClinicalTrials.gov identifier
NCT05844423
Study number
VAX24-112
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