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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

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What is being tested

31-valent pneumococcal conjugate vaccine

+ Seasonal Influenza Vaccine (SIV) (Flublok)

+ Placebo

Biological
Who is being recruted

Bacterial Infections and Mycoses+7

+ Bacterial Infections

+ Infections

Over 50 Years
+26 Eligibility Criteria
See all eligibility criteria
How is the trial designed

Prevention Study

Phase 3
Interventional
Study Start: January 2026
See protocol details

Summary

Principal SponsorVaxcyte, Inc.
Study ContactClinical Development
Last updated: January 27, 2026
Sourced from a government-validated database.Claim as a partner

Study start date: January 12, 2026

Actual date on which the first participant was enrolled.

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.

Official TitleA 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 
NCT07365826
Principal SponsorVaxcyte, Inc.
Study ContactClinical Development
Last updated: January 27, 2026
Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.
Design Details

1300 patients to be enrolled

Total number of participants that the clinical trial aims to recruit.

Prevention Study

Prevention studies aim to stop a disease from developing. They often involve people at risk and test things like vaccines, lifestyle changes, or preventive medications.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.
Conditions
Criteria

Any sex

Biological sex of participants that are eligible to enroll.

Over 50 Years

Range of ages for which participants are eligible to join.

Healthy volunteers allowed

If individuals who are healthy and do not have the condition being studied can participate.

Conditions

Pathology

Bacterial Infections and MycosesBacterial InfectionsInfectionsLung DiseasesPneumococcal InfectionsPneumoniaRespiratory Tract DiseasesRespiratory Tract InfectionsStreptococcal InfectionsGram-Positive Bacterial Infections

Criteria

8 inclusion criteria required to participate
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.
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18 exclusion criteria prevent from participating
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.
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Study Plan

Find out more about all the medication administered in this study, their detailed description and what they involve.
Treatment Groups
Study Objectives

2 intervention groups are designated in this study

This study does not include a placebo group 

Treatment Groups

Group I

Experimental
Participants will receive placebo administered via intramuscular injection at Day 1, concomitantly administered with SIV, followed by VAX-31 at Month 1.

Group II

Experimental
Participants 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.

Study Objectives

Primary Objectives

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.

This study has 25 locations

Recruiting

Hope Research Institute

Phoenix, United StatesSee the location
Recruiting

Tekton Research at Fort Collins

Fort Collins, United States
Recruiting

University Clinical Research - Deland

DeLand, United States
Recruiting

CenExel Research Centers of America

Hollywood, United States
Recruiting
25 Study Centers