Safety, Tolerability, and Immunogenicity Study of a 31-Valent Pneumococcal Conjugate Vaccine (VAX-31) in Adults

A Phase 1/2, Randomized, Observer-Blind, Dose-Finding, Active-Controlled, Parallel-Group, Clinical Study to Evaluate the Safety, Tolerability, and Immunogenicity of a 31-Valent Pneumococcal Conjugate Vaccine (VAX-31) in Healthy Adults Aged 50 Years and Older

The objective of the study is to evaluate the safety, tolerability and immunogenicity of a single injection of VAX-31 at 3 dose levels compared to Prevnar 20™ (PCV20) in adults 50 to 64 years of age in Stage 1. Stage 2 will evaluate the safety, tolerability, and immunogenicity of a single injection of VAX-31 at 3 dose levels compared to PCV20 in adults aged 50 years and older.

Study Overview

• Status: Completed
• Conditions: Pneumococcal Vaccines
• Intervention / Treatment: Biological: 31 valent pneumococcal conjugate vaccine; Biological: 20 valent pneumococcal conjugate vaccine

• Study Type: Interventional
• Enrollment (Actual): 1015
• Phase: Phase 2; Phase 1

Contacts and Locations

Study Locations

• United States
  • Alabama
    • Mobile, Alabama, United States, 36608
      • AMR Mobile
  • Arizona
    • Phoenix, Arizona, United States, 85282
      • AMR Phoenix
  • Florida
    • Hollywood, Florida, United States, 33024
      • Research Centers of America
    • Jupiter, Florida, United States, 33458
      • Health Awareness
    • Melbourne, Florida, United States, 32934
      • Optimal Research
    • Sunrise, Florida, United States, 33351
      • Precision Clinical Research
  • Georgia
    • Savannah, Georgia, United States, 31406
      • Velocity Clinical Research, Savannah
  • Illinois
    • Flossmoor, Illinois, United States, 60422
      • Healthcare Research Network II, LLC
  • Kansas
    • Lenexa, Kansas, United States, 66219
      • Johnson County Clin-Trials
  • Michigan
    • Detroit, Michigan, United States, 48076
      • DM Clinical Research - Detroit
  • Nebraska
    • Omaha, Nebraska, United States, 68134
      • Velocity Clinical Research Omaha
  • Nevada
    • Las Vegas, Nevada, United States, 89106
      • WR-CRCN
  • New Jersey
    • Toms River, New Jersey, United States, 08755
      • CenExel AMRI
  • New York
    • Rochester, New York, United States, 14609
      • Rochester Clinical Research
  • Ohio
    • Cincinnati, Ohio, United States, 45212
      • CTI Clinical Research Center
    • Cleveland, Ohio, United States, 44122
      • Velocity Clinical Research, Cleveland
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19107
      • DM Clinical Research - Philadelphia
  • Rhode Island
    • Warwick, Rhode Island, United States, 02886
      • Velocity Clinical Research
  • South Carolina
    • North Charleston, South Carolina, United States, 29405
      • Coastal Carolina Research
  • Tennessee
    • Knoxville, Tennessee, United States, 37909
      • AMR Knoxville
  • Texas
    • Fort Worth, Texas, United States, 76135
      • Benchmark Research
    • San Angelo, Texas, United States, 76904
      • Benchmark Research
  • Utah
    • Salt Lake City, Utah, United States, 84107
      • CenExel JBR Clinical Research
  • Virginia
    • Charlottesville, Virginia, United States, 22911
      • Charlottesville Medical Research
    • Newport News, Virginia, United States, 23606
      • Health Research of Hampton Roads

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Male or female aged 50 to 64 years (inclusive) for Stage 1, or 50 years and older (inclusive) for Stage 2 at the time of randomization into the study.
2. Able and willing to complete the informed consent process.
3. Available for clinical follow-up through the last study visit at 6 months after the study vaccination.
4. In good general health as determined by medical history, vital signs, physical examination, and clinical judgment of the Investigator.
5. Willing to have blood samples collected, stored indefinitely, and used for research purposes.
6. Able to provide proof of identity to the satisfaction of the study staff completing the enrollment process.
7. Women of childbearing potential, defined as premenopausal females capable of becoming pregnant, must have a negative urine pregnancy test immediately prior to randomization and agree to use acceptable contraception
8. Able to access and use a smartphone, tablet, computer, or other device connected to Wi-Fi or cellular network for completion of an electronic diary.

Exclusion Criteria:

1. Previous pneumococcal disease (either confirmed or self-reported).
2. Previous receipt of a licensed or investigational pneumococcal vaccine.
3. Receipt of any investigational study product within 30 days prior to enrollment into the study, currently participating in another interventional investigational study, or having plans to receive another investigational product(s) while on study.
4. Planned or actual administration of any licensed vaccine during the period starting 30 days before enrollment into the study through Month 1.
5. Physical examination indicating any clinically significant medical condition.
6. Body Temperature >38.0°C (>100.4°F) or acute illness within 3 days prior to study vaccination (subject may be rescheduled).
7. Previous or existing diagnosis of HIV, Hepatitis B, or Hepatitis C.
8. History of severe allergic reaction with generalized urticaria, angioedema, or anaphylaxis.
9. Female who is pregnant, breastfeeding, or planning to become pregnant during study participation.
10. Bleeding disorder diagnosed by a doctor (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) resulting in clinically significant bruising or bleeding difficulties with IM injections or blood draws.
11. Any other chronic or clinically significant medical condition that, in the opinion of the Investigator, would jeopardize the safety or rights of the subject or confound evaluation of the study vaccine.
12. Any medical, psychiatric, or social condition that in the judgment of the Investigator is a contraindication to protocol participation or impairs a subject's ability to give informed consent.
13. Received blood or blood product (including Immune Globulin IV) within 90 days prior to enrollment into the study.

14. Received systemic corticosteroids (except for inhaled, topical, intra-articular) for

    ≥14 consecutive days and has not completed treatment ≤30 days prior to enrollment into the study.

15. Receiving immunosuppressive therapy.
16. History of malignancy ≤5 years before enrollment, except for adequately treated basal cell or squamous cell skin cancer or in situ cervical cancer

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group 1; Participants received a single low dose of VAX-31 administered as an intramuscular injection at Day 1. 1.1 mcg for all serotypes with the exception of serotypes 1, 5, and 22F which is 1.65 mcg.	Biological: 31 valent pneumococcal conjugate vaccine; 0.5 ml dose of VAX-31 was administered into the deltoid muscle at Day 1
Experimental: Group 2; Participants received a single mid dose of VAX-31 administered as an intramuscular injection at Day 1. 2.2 mcg for all serotypes with the exception of serotypes 1, 5, and 22F which is 3.3 mcg.	Biological: 31 valent pneumococcal conjugate vaccine; 0.5 ml dose of VAX-31 was administered into the deltoid muscle at Day 1
Experimental: Group 3; Participants received a single high dose of VAX-31 administered as an intramuscular injection at Day 1. 3.3 mcg for all serotypes with the exception of serotypes 1, 5, and 22F which is 4.4 mcg.	Biological: 31 valent pneumococcal conjugate vaccine; 0.5 ml dose of VAX-31 was administered into the deltoid muscle at Day 1
Active Comparator: Group 4; Participants received a single intramuscular injection of the standard dose of PCV20 at Day 1.	Biological: 20 valent pneumococcal conjugate vaccine; 0.5 ml dose of PCV20 was administered into the deltoid muscle at Day 1; Other Names: Prevnar 20™; PCV20

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Subjects Reporting Solicited Local Reactions Within 7 Days After Vaccination (Redness, Swelling, and Pain at Injection Site) in Each Age Group	Solicited local reactions include redness/erythema, swelling/induration, and pain at injection site within 7 days after vaccination in each age group.	7 days after vaccination
Percentage of Subjects Reporting Solicited Systemic Events Within 7 Days After Vaccination (Fever, Headache, Fatigue, Muscle Pain, and Joint Pain) in Each Age Group Vaccination in Each Age Group	Solicited systemic reactions include fever, headache, fatigue, muscle pain, and joint pain.	7 days after vaccination
Percentage of Subjects Reporting Unsolicited Adverse Event in Each Age Group	Percentage of participants in each age group with adverse events (AEs) whose date of onset occurs after the study vaccine and within the 1 month after vaccination.	1 month after vaccination
Percentage of Subjects Reporting Serious Adverse Event	Percentage of participants with SAEs.	6 months after vaccination
Percentage of Subjects Reporting New Onset of Chronic Illness	Percentage of participants with NOCIs	6 months after vaccination
Percentage of Subjects Reporting Medically Attended Adverse Event	Percentage of participants with MAAEs.	6 months after vaccination

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Subjects With Adverse Events Due to Clinically Significant Laboratory Values	Laboratory values that resulted in treatment and reporting as adverse events 1 month following vaccination.	1 month after vaccination
Percentage of Participants With a Shift From Normal at Baseline to Abnormal at Post-vaccination in Safety Laboratory Parameters (Hematology, Clinical Chemistry, Urinalysis)	Shifts from Normal at Baseline to Abnormal on Month 1 (30 days after vaccination) in Hematology, Clinical Chemistry and Urinalysis Parameters Occurring in Subjects Aged 50+ Years.	1 month after vaccination
31 VAX-31 Pneumococcal Serotype-specific OPA Geometric Mean Titer	Antibody geometric mean titers as measured by OPA for the 31 pneumococcal serotypes in VAX-31.	1 month after vaccination
31 VAX-31 Pneumococcal Serotype-specific IgG Geometric Mean Concentration	Antibody geometric mean concentrations as measured by IgG for the 31 pneumococcal serotypes in VAX-31.	1 month after vaccination

Collaborators and Investigators

• Sponsor: Vaxcyte, Inc.
• Investigators: Study Director: Clinical Development, Vaxcyte, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): November 8, 2023
• Primary Completion (Actual): July 17, 2024
• Study Completion (Actual): July 17, 2024

Study Registration Dates

• First Submitted: November 10, 2023
• First Submitted That Met QC Criteria: November 20, 2023
• First Posted (Actual): November 30, 2023

Study Record Updates

• Last Update Posted (Actual): July 28, 2025
• Last Update Submitted That Met QC Criteria: July 8, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Immunologic Factors; Physiological Effects of Drugs; Heptavalent Pneumococcal Conjugate Vaccine; Vaccines
• Other Study ID Numbers: VAX31-101

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: 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.
• IPD Sharing Time Frame: Individual participant data will be shared after deidentification and made available starting 6 months after initial product approval.
• IPD Sharing Access Criteria: Criteria will depend on the specific proposal received and may include qualification of the scientific researchers, potential contribution to the research field, scientific rigor of statistical and analytical methods, and other criteria appropriate for the proposal.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No