A Phase 2 interventional study of 0.5 mL of the low dose VAX-31 and 0.5 mL of the mid dose VAX-31 in Pneumococcal Vaccines, sponsored by Vaxcyte, Inc.. Active, not recruiting at 48 sites in 2 countries. Open to participants aged 42 Days to 89 Days, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-15.
Sponsored by Vaxcyte, Inc. · Phase 2, Interventional, and Prevention
The objective of the study is to evaluate the safety, tolerability, and immunogenicity of 4 injections of VAX-31 (at 4 dose levels) compared to PCV20 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 approximately 352 subjects. Stage 3 of the study will enroll approximately 500 subjects.
2,044 studies on the registry are indexed under Pneumonia; 283 are open to participants now.
This study's enrollment of 900 is above the median of 106 across 1,247 interventional studies indexed under Pneumonia.
Browse Pneumonia studies →Vaxcyte, Inc. is the lead sponsor of 9 studies on the registry; 1 is open to participants now.
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Exclusion Criteria:
Participants will receive 4 doses of VAX-31 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of four dose levels.
Biological: 0.5 mL of the low dose VAX-31
Participants will receive 4 doses of VAX-31 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of four dose levels.
Biological: 0.5 mL of the mid dose VAX-31
Participants will receive 4 doses of VAX-31 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of four dose levels.
Biological: 0.5 mL of the high dose VAX-31
Participants will receive 4 doses of PCV20 administered as an intramuscular injection of the standard dose at 2, 4, 6, and 12-15 months of age.
Biological: 0.5 mL dose of PCV20
Participants will receive 4 doses of VAX-31 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of four dose levels.
Biological: 0.5 mL of the High-PFS dose VAX-31
31 valent pneumococcal conjugate vaccine
31 valent pneumococcal conjugate vaccine
31 valent pneumococcal conjugate vaccine
20 valent pneumococcal conjugate vaccine
31 valent pneumococcal conjugate vaccine
Percentage of subjects with any solicited local injection site adverse events (AE) within 7 days after each vaccination
Solicited local reactions include erythema, edema, and tenderness at the injection site
Time frame: 7 days after each vaccination
Percentage of subjects with any solicited systemic AE within 7 days after each vaccination
Solicited systemic reactions include fever, irritability, decreased appetite, decreased sleep, and increased sleep
Time frame: 7 days after each vaccination
Percentage of subjects with any unsolicited AE within 1 month after each vaccination
Percentage of subjects with unsolicited AE
Time frame: 1 months after each vaccination
Percentage of subjects with any medically attended adverse events (MAAE) within 6 months after last vaccination
Percentage of subjects with MAAE
Time frame: 6 months after last vaccination
Percentage of subjects with any Serious Adverse Events (SAE) within 6 months after last vaccination
Percentage of subjects with SAE
Time frame: 6 months after last vaccination
Percentage of subjects with any new onset of chronic illness (NOCI) within 6 months after last vaccination
Percentage of subjects with NOCI
Time frame: 6 months after last vaccination
Percentage of subjects achieving a serotype-specific anti-pneumococcal IgG antibody concentration ≥0.35 mcg/mL 1 month after Dose 3
Percentage of subjects achieving a serotype-specific anti-pneumococcal IgG antibody concentration ≥0.35 mcg/mL
Time frame: 1 month after Dose 3
Serotype-specific IgG antibody geometric mean concentration (GMC) 1 month after Dose 3
Antibody geometric mean concentrations as measured by IgG for the 31 pneumococcal serotypes in VAX-31
Time frame: 1 month after Dose 3
Serotype-specific IgG antibody GMC 1 month after Dose 4
Antibody geometric mean concentrations as measured by IgG for the 31 pneumococcal serotypes in VAX-31
Time frame: 1 month after Dose 4
Plan to share: Yes — Vaxcyte is committed to providing access to anonymized data from the company's clinical trials for the purpose of legitimate scientific research. Requests for data may be addressed to datasharing@vaxcyte.com. Requests must be accompanied by a detailed analysis plan and will be reviewed for scientific validity. Data will be made available after initial product approval. Sharing of data may require execution of a data-sharing agreement.
Supporting information: Study protocol
No publications or documents are linked to this record.
This study is active, not recruiting, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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Vaxcyte, Inc.