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Pneumococcal VaccinesPhase 2NCT05844423

Safety, Tolerability, and Immunogenicity of a 24-Valent Pneumococcal Conjugate Vaccine (VAX-24) in Healthy Infants

A Phase 2 study testing 0.5 ml dose of 1.1 mcg VAX-24, 0.5 ml dose of PCV20 and 0.5 ml dose of 2.2 mcg VAX-24 in people with Pneumococcal Vaccines, run by Vaxcyte, Inc. at 32 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

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. Read more about this study

Who is it for?
Ages 42 to 89 daysHealthy volunteers can take part
Conditions the study is for
Pneumococcal Vaccines
What is being tested?
0.5 ml dose of 1.1 mcg VAX-24, 0.5 ml dose of PCV20 and 0.5 ml dose of 2.2 mcg VAX-24
Could I receive a placebo?
No, everyone receives an active treatment
How many people
802 participants
Where
32 sitesUnited States
Study dates
29 Mar 2023to 25 Aug 2025
Phase
Phase 2
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 42 to 89 days
  • All sexes
  • Healthy volunteers accepted
  • Child

Who may be able to join

  • 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.

Who cannot join

  • 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.
Show all 14Show fewer
  • 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.

Trial locations and contacts

32 sites in 1 country.

32 sites in 1 country

United States32 sites
  • Kentucky Pediatric/ Adult Research

    Bardstown, Kentucky, 40004

  • Ventavia Research Group

    Burleson, Texas, 76028

  • Pediatric Research of Charlottesville, LLC

    Charlottesville, Virginia, 22902

  • UPMC Bass Wolfson Cranberry

    Cranberry Township, Pennsylvania, 16066

  • Ohio Pediatric Research Assn.

    Dayton, Ohio, 45414

  • Allegheny Health and Wellness Pavilion

    Erie, Pennsylvania, 16506

  • Meridian Clinical Research

    Hastings, Nebraska, 68901

  • ACC Pediatric Research

    Haughton, Louisiana, 71037

  • Ventavia

    Houston, Texas, 77008

  • Kool Kids Pediatrics

    Houston, Texas, 77065

  • Pediatric Associates

    Houston, Texas, 77087

  • UPMC Children's Community Pediatrics South Hills-Jefferson Hills

    Jefferson Hills, Pennsylvania, 15025

  • The Children's Clinic of Jonesboro, P.A.

    Jonesboro, Arkansas, 72401

  • Holston Medical Group

    Kingsport, Tennessee, 37660

  • Alliance for Multispecialty Research

    Layton, Utah, 84041

  • Midwest Children's Health Research Institute

    Lincoln, Nebraska, 68504

  • Midwest Children's Health Research Institute

    Lincoln, Nebraska, 68505

  • Midwest Children's Health Research Institute

    Lincoln, Nebraska, 68516

  • Midwest Children's Health Research Institute

    Lincoln, Nebraska, 68522

  • Madera Family Medical Group

    Madera, California, 93637

  • Alliance for Multispecialty Research

    Murray, Utah, 84107

  • Palmetto Pediatrics, PA

    North Charleston, South Carolina, 29406

  • UPMC Primary Care Center Oakland

    Pittsburgh, Pennsylvania, 15213

  • UPMC Children's Community Pediatrics Bass Wolfson-Squirrel Hill

    Pittsburgh, Pennsylvania, 15217

  • UPMC Children's Community Pediatrics-Castle Shannon

    Pittsburgh, Pennsylvania, 15234

  • Alliance for Multispecialty Research

    Provo, Utah, 84604

  • Pediatric Center

    Richmond, Texas, 77469

  • Alliance for Multispecialty Research

    Roy, Utah, 84067

  • Tribe Clinical Research at Parkside Pediatrics

    Simpsonville, South Carolina, 29680

  • Coastal Pediatric Research

    Summerville, South Carolina, 29486

  • Alliance for Multispecialty Research

    Syracuse, Utah, 84075

  • Jedidiah Clinical Research

    Tampa, Florida, 33617

Other trials in United States

About this study

Official title: Randomized, Observer-Blind, Active-Controlled, Dose-Finding Study to Evaluate the Safety, Tolerability, and Immunogenicity of 24-Valent PCV (VAX-24) in Infants Given 4 Doses at 2, 4, 6, and 12-15 Months of Age With Pediatric Vaccines

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.

Being tested
0.5 ml dose of 1.1 mcg VAX-24, 0.5 ml dose of PCV20, 0.5 ml dose of 2.2 mcg VAX-24, 0.5 ml dose of 2.2/4.4 mcg VAX-24
Keywords
24 valent PCV, Pneumonia, Pneumococcal Infection
Medical subject headings
Pneumonia, Pneumococcal Infections

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • 0.5 ml dose of 1.1 mcg VAX-24Biological

    24 valent pneumococcal conjugate vaccine

  • 0.5 ml dose of PCV20Biological

    20 valent pneumococcal conjugate vaccine

  • 0.5 ml dose of 2.2 mcg VAX-24Biological

    24 valent pneumococcal conjugate vaccine

  • 0.5 ml dose of 2.2/4.4 mcg VAX-24Biological

    24 valent pneumococcal conjugate vaccine

Study groups in NCT05844423
Study groupRoleWhat they receive
VAX-24 LowExperimentalParticipants will receive 4 doses of VAX-24 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of three dose levels.
Receives: Biological: 0.5 ml dose of 1.1 mcg VAX-24
VAX-24 MidExperimentalParticipants will receive 4 doses of VAX-24 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of three dose levels.
Receives: Biological: 0.5 ml dose of 2.2 mcg VAX-24
VAX-24 MixedExperimentalParticipants will receive 4 doses of VAX-24 administered as an intramuscular injection at 2, 4, 6, and 12-15 months of age at one of three dose levels.
Receives: Biological: 0.5 ml dose of 2.2/4.4 mcg VAX-24
PCV20Active comparatorParticipants 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.
Receives: Biological: 0.5 ml dose of PCV20

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Percentage of participants 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

    Measured: 7 days after each vaccination

  2. Percentage of participants with any solicited systemic AE within 7 days after each vaccination

    Solicited systemic reactions include fever, irritability, decreased appetite, decreased sleep, and increased sleep

    Measured: 7 days after each vaccination

  3. Percentage of participants with any related Serious Adverse Events (SAE) within 6 months after last vaccination

    Percentage of participants with related SAE

    Measured: 6 months after last vaccination

Secondary outcomes (16)
  1. Percentage of subjects with any unsolicited AE within 1 month after each vaccination

    Percentage of subjects with any unsolicited AE

    Measured: 1 month after each vaccination

  2. Percentage of subjects with any unsolicited AE from Dose 1 through 1 month post-Dose 3

    Percentage of subjects with any unsolicited AE between first and 3rd vaccination in the primary series

    Measured: First vaccination (Dose 1) through 1 month after third vaccination (Dose 3)

  3. Percentage of subjects with any AE resulting in discontinuation of study within 6 months after last vaccination

    Percentage of subjects with any AE resulting in discontinuation of study

    Measured: 6 months after last vaccination

  4. Percentage of subjects with any new onset of chronic illness (NOCI) within 6 months after last vaccination

    Percentage of subjects with any NOCI

    Measured: 6 months after last vaccination

  5. Percentage of subjects with any medically attended adverse events (MAAE) within 6 months after last vaccination

    Percentage of subjects with any MAAE

    Measured: 6 months after last vaccination

  6. Percentage of subjects with any SAE within 6 months after last vaccination

    Percentage of subjects with any SAE

    Measured: 6 months after last vaccination

  7. Percentage of subjects achieving an anti-pneumococcal Immunoglobulin G (IgG) antibody concentration ≥0.35 mcg/mL 1 month after Dose 3

    Percentage of subjects achieving an anti-pneumococcal IgG antibody concentration ≥0.35 mcg/mL

    Measured: 1 month after Dose 3

  8. Percentage of subjects achieving an anti-pneumococcal IgG antibody concentration ≥0.35 mcg/mL 1 month after Dose 4

    Percentage of subjects achieving an anti-pneumococcal IgG antibody concentration ≥0.35 mcg/mL

    Measured: 1 month after Dose 4

  9. IgG antibody Geometric Mean Concentration (GMC) 1 month after Dose 3

    Antibody geometric mean concentrations as measured by IgG for the 24 pneumococcal serotypes in VAX-24

    Measured: 1 month after Dose 3

  10. IgG antibody GMC 1 month after Dose 4

    Antibody geometric mean concentrations as measured by IgG for the 24 pneumococcal serotypes in VAX-24

    Measured: 1 month after Dose 4

  11. Opsonophagocytic activity (OPA) Geometric Mean Titer (GMT) 1 month after Dose 3

    Antibody geometric mean titers s as measured by OPA for the 24 pneumococcal serotypes in VAX-24

    Measured: 1 month after Dose 3

  12. OPA GMT 1 month after Dose 4

    Antibody geometric mean titers s as measured by OPA for the 24 pneumococcal serotypes in VAX-24

    Measured: 1 month after Dose 4

  13. IgG Geometric Mean Fold Ratio (GMFR) before Dose 4 to 1 month after Dose 4

    Antibody geometric mean fold ratio as measured by IgG for the 24 pneumococcal serotypes in VAX-24

    Measured: Pre-Dose 4 to 1 month after Dose 4

  14. OPA GMFR before Dose 4 to 1 month after Dose 4

    Antibody geometric mean fold rise as measured by OPA for the 24 pneumococcal serotypes in VAX-24

    Measured: Pre-Dose 4 to 1 month after Dose 4

  15. Percentage of subjects achieving at least a 4-fold increase in IgG from pre-Dose 4 to 1 month post Dose 4

    Geometric mean concentration with a at least a 4-fold increase in IgG antibodies for the 24 pneumococcal serotypes in VAX-24

    Measured: Pre-Dose 4 to 1 month after Dose 4

  16. Percentage of subjects achieving at least a 4-fold increase in OPA titers from pre-Dose 4 to 1 month post Dose 4

    Geometric mean titer with a at least a 4-fold increase in OPA titers for the 24 pneumococcal serotypes in VAX-24

    Measured: Pre-Dose 4 to 1 month after Dose 4

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted6 May 2023
  2. Study start29 Mar 2023
  3. Primary completion25 Aug 2025
  4. Study completion25 Aug 2025

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
802 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05844423
Sponsor's protocol ID
VAX24-112
Status last verified
Sep 2025
First submitted
24 Apr 2023
Last updated
11 Sep 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
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.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing 0.5 ml dose of 1.1 mcg VAX-24, 0.5 ml dose of PCV20 and 0.5 ml dose of 2.2 mcg VAX-24 in people with Pneumococcal Vaccines, run by Vaxcyte, Inc. at 32 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 11 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 32 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of participants with any solicited local injection site Adverse Events (AE) within 7 days after each vaccination (time frame: 7 days after each vaccination). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Sep 2025.

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