A Clinical Study to Evaluate the Safety, Tolerability, and Immunogenicity of VAX-31 With Influenza Vaccine in Adults ≥ 50 Years of Age
A Phase 3, Randomized, Double-Blind, Placebo-Controlled Clinical Study to Evaluate the Safety, Tolerability, and Immunogenicity of VAX-31 Concomitantly Administered With Seasonal Influenza Vaccine in Healthy Subjects 50 Years of Age and Older
1 other identifier
interventional
1,390
1 country
25
Brief Summary
This is a Phase 3, randomized, double-blind study to evaluate the safety and immunogenicity of VAX-31 and seasonal influenza vaccine in pneumococcal-naïve adults ≥ 50 years when the two vaccines are administered at the same visit or separately.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for phase_3
Started Jan 2026
Shorter than P25 for phase_3
25 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
Study Start
First participant enrolled
January 12, 2026
CompletedFirst Submitted
Initial submission to the registry
January 22, 2026
CompletedFirst Posted
Study publicly available on registry
January 26, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
March 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
March 1, 2027
March 31, 2026
March 1, 2026
1.1 years
January 22, 2026
March 25, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (6)
For each of the 32 serotypes (the 31 serotypes included in VAX-31, and serotype 20B), the ratio (co-administration group to sequential administration group) of opsonophagocytic activity (OPA) geometric mean titers (GMT) in evaluable participants
1 Month after VAX-31 vaccination
For each of the strains in SIV, the ratio (co-administration group to sequential administration group) of hemagglutination inhibition (HAI) GMT in evaluable participants
1 Month after SIV administration
Percentage of participants reporting solicited local adverse events (AE) within 7 days after Day 1 and Month 1 vaccination (redness, swelling, and pain at injection site) in each group
7 days after each vaccination
Percentage of participants reporting solicited systemic AE within 7 days after Day 1 and Month 1 vaccination (fever, headache, fatigue, muscle pain, and joint pain) in each group
7 days after each vaccination
Percentage of participants reporting unsolicited AE within 1 month after Day 1 and Month 1 vaccination in each group
7 days after each vaccination
Percentage of participants reporting NOCI, MAAE, and SAE within 6 months after last vaccination in each group
6 Months after last vaccination
Secondary Outcomes (1)
For each of the 32 serotypes (the 31 serotypes included in VAX-31, and serotype 20B), the ratio (co-administration group to sequential administration group) of IgG geometric mean concentrations (GMC) in evaluable participants
1 month after VAX-31 administration
Study Arms (2)
VAX-31 + SIV
EXPERIMENTALParticipants will receive a single dose of VAX-31 administered as an intramuscular injection at Day 1, concomitantly administered with SIV, followed by placebo at Month 1.
Placebo + SIV
EXPERIMENTALParticipants will receive placebo administered via intramuscular injection at Day 1, concomitantly administered with SIV, followed by VAX-31 at Month 1.
Interventions
0.5 mL of VAX-31 will be administered into the deltoid muscle
0.5 mL of SIV into the deltoid muscle
Eligibility Criteria
You may qualify if:
- Male or female ≥50 years of age (inclusive) at the time of randomization into the study.
- Able and willing to complete the informed consent process.
- Available for clinical follow-up through the last study visit at 7 months after the first study vaccination.
- In good general health or with stable underlying chronic condition(s), as determined by medical history, oral temperature, physical examination, and clinical judgment of the Investigator.
- Willing to have blood samples collected and used for research purposes.
- Able to provide proof of identity to the satisfaction of the study site personnel completing the enrollment process.
- Female subjects of childbearing potential, defined as premenopausal females capable of becoming pregnant, must have a negative urine pregnancy test at Screening and immediately prior to each vaccination and agree to use acceptable contraception, if heterosexually active. Female subjects who are not abstinent from heterosexual intercourse must agree to consistently practice contraception at least 7 days prior to vaccination and through their last study visit. Male subjects with partners of childbearing potential must agree to practice an acceptable contraception method (\[use condoms with or without spermicide\] or have undergone a vasectomy) from Day 1 through their last study visit. Note: A history of amenorrhea for at least 12 months without an alternative medical cause is required for a female to be considered postmenopausal in the study.
- Able to access and use a device connected to Wi-Fi or cellular network for completion of an electronic diary (eDiary).
You may not qualify if:
- History of IPD or pneumococcal pneumonia (either confirmed or self-reported) at any age.
- Previous receipt of a licensed or investigational pneumococcal vaccine at any age.
- Previous receipt of an influenza vaccine from the current season; receipt of any influenza vaccine (licensed or investigational) within 6 months prior to Day 1; or receipt/planned receipt of any licensed or investigational non-study influenza vaccine during study participation.
- Receipt of any investigational product within 30 days prior to Day 1, currently participating in another interventional investigational study, or having plans to receive another investigational product(s) while on study.
- Planned or actual administration of any licensed vaccine within 30 days prior to Day 1.
- Body temperature \>38.0°C (\>100.4°F) or acute illness within 3 days prior to study vaccination (participant may be rescreened).
- Current diagnosis of human immunodeficiency virus (HIV), Hepatitis B, or Hepatitis C.
- History of severe allergic reaction with generalized urticaria, angioedema, or anaphylaxis to any previous vaccination.
- History of Guillain-Barré syndrome.
- Individual who is pregnant, breastfeeding, or planning to become pregnant during study participation.
- Has a known or suspected immunocompromising condition, including, but not limited to, leukemia, lymphoma, chronic renal failure, or congenital or acquired immunodeficiency.
- 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.
- Receipt of blood or blood product (including polyclonal intravenous immunoglobulin) within 60 days prior to Day 1.
- Receiving immunosuppressive therapy.
- Received any part of a ≥14-day course of systemic corticosteroids (prednisone equivalent \>10 mg/day) within 14 days of study vaccinations. Note: Receipt of a ≥14-day course of systemic corticosteroids equivalent to ≤10 mg/day is permitted, as are inhaled, nebulized, topical, intra-articular, and intrabursal corticosteroids.
- +3 more criteria
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Vaxcyte, Inc.lead
Study Sites (25)
Hope Research Institute
Phoenix, Arizona, 85032, United States
Tekton Research at Fort Collins
Fort Collins, Colorado, 80525, United States
University Clinical Research - Deland
DeLand, Florida, 32720-0834, United States
CenExel Research Centers of America
Hollywood, Florida, 33024, United States
Health Awareness
Jupiter, Florida, 33458, United States
Accel Research Sites - Lakeland
Lakeland, Florida, 33803, United States
Accel Research Sites - Largo
Largo, Florida, 33777, United States
Precision Clinical Research
Sunrise, Florida, 33351, United States
Velocity Valparaiso
Valparaiso, Indiana, 46383, United States
Johnson County ClinTrials
Lenexa, Kansas, 66219, United States
AMR Lexington
Lexington, Kentucky, 40509, United States
DM Clinical Research - Detroit
Detroit, Michigan, 48076, United States
Velocity Omaha
Omaha, Nebraska, 68134, United States
Rochester Clinical Research
Rochester, New York, 14609, United States
CTI Clinical Research Center
Cincinnati, Ohio, 45212, United States
Coastal Carolina Research Center
North Charleston, South Carolina, 29405, United States
DelRicht Research - Hendersonville
Hendersonville, Tennessee, 37075, United States
AMR Knxoville
Knoxville, Tennessee, 37909, United States
Tekton Research at Austin
Austin, Texas, 78745, United States
REX Clinical Trials
Beaumont, Texas, 77701, United States
Epic Medical Research
DeSoto, Texas, 75115, United States
CenExel JBR Clinical Research
Salt Lake City, Utah, 84107, United States
Charlottesville Medical Research Center
Charlottesville, Virginia, 22911, United States
Health Research of Hampton Roads, Inc.
Newport News, Virginia, 23606, United States
Clinical Research Partners, LLC.
Richmond, Virginia, 23226, United States
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Study Design
- Study Type
- interventional
- Phase
- phase 3
- Allocation
- RANDOMIZED
- Masking
- QUADRUPLE
- Who Masked
- PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
- Purpose
- PREVENTION
- Intervention Model
- PARALLEL
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
January 22, 2026
First Posted
January 26, 2026
Study Start
January 12, 2026
Primary Completion (Estimated)
March 1, 2027
Study Completion (Estimated)
March 1, 2027
Last Updated
March 31, 2026
Record last verified: 2026-03
Data Sharing
- IPD Sharing
- Will share
- Shared Documents
- STUDY PROTOCOL
- Time Frame
- Individual participant data will be shared after deidentification and made available starting 6 months after initial product approval.
- 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.
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.