A Study to Learn About the Safety of an Expanded Pneumococcal Vaccine in Healthy Infants

May 26, 2026 updated by: Pfizer

A PHASE 3, RANDOMIZED, DOUBLE-BLINDED TRIAL TO EVALUATE THE SAFETY AND TOLERABILITY OF A MULTIVALENT PNEUMOCOCCAL CONJUGATE VACCINE IN HEALTHY INFANTS

The purpose of this study is to learn about the safety of a new pneumococcal vaccine and how the new pneumococcal vaccine helps to fight against germs that can cause pneumonia (lung infections), meningitis (brain infections), and otitis media (ear infections) in infants when compared to the pneumococcal vaccine that is currently in use, 20vPnC (Prevnar 20®).

This study will test if the new pneumococcal vaccine is as safe as the one that is currently in use. This new vaccine can possibly provide additional protection against germs that cause pneumococcal disease that are not included in the vaccines that are currently given to infants. Pneumococcal disease includes a variety of infections caused by a specific germ, Streptococcus pneumoniae.

There are two groups in this study. All participants will be assigned to one of the two groups. This study is seeking participants who are:

- infants who are about 2 months of age

About 2400 infants will be assigned by chance to one of the two groups to receive either PG4 (new vaccine) or 20vPnC (currently in use) into the left thigh muscle at 2, 4, 6, and 12 to 15 months of age.

Infants will take part in this study for about 16 to 19 months (about 1 and a half years). During this time, infants will have 6 study clinic visits and 1 phone call. At these study clinic visits, parent(s)/legal guardian(s) will be asked if the infant experienced any side effects. A side effect is an unintentional or unexpected reaction to a vaccine.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

2400

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • Florida
      • Estero, Florida, United States, 33928
        • Not yet recruiting
        • Starz Pediatrics
    • Georgia
      • Union City, Georgia, United States, 30291
        • Not yet recruiting
        • Rophe Adult and Pediatric Medicine/SKYCRNG
    • Idaho
      • Idaho Falls, Idaho, United States, 83404
        • Not yet recruiting
        • Rosemark Women Care Specialists
    • Kentucky
      • Bardstown, Kentucky, United States, 40004
        • Not yet recruiting
        • Kentucky Pediatric/ Adult Research
    • Massachusetts
      • Fall River, Massachusetts, United States, 02721
        • Not yet recruiting
        • Pediatric Associates of Fall River
    • Ohio
      • South Euclid, Ohio, United States, 44121
        • Recruiting
        • Senders Pediatrics
    • Oregon
      • Gresham, Oregon, United States, 97030
        • Not yet recruiting
        • Cyn3rgy Research Corporation
    • South Carolina
      • Simpsonville, South Carolina, United States, 29680
        • Recruiting
        • Tribe Clinical Research LLC. at Parkside Pediatrics Five Forks
    • Virginia
      • Gordonsville, Virginia, United States, 22942
        • Recruiting
        • Pediatric Research of Charlottesville, LLC.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Infants who are about 2 months of age
  • Healthy infants determined by clinical assessment, including medical history and clinical judgment, to be eligible for the study.

Exclusion Criteria:

  • History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis).
  • Major known congenital malformation or serious chronic disorder.
  • Other acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the participant inappropriate for entry into this study.
  • Previous vaccination with any licensed or investigational pneumococcal vaccine, or planned receipt through study participation.

Study Plan

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

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: PG4 (intramuscular)
Multivalent Pneumococcal Vaccine
Biological: PG4
Multivalent Pneumococcal Vaccine
Active Comparator: 20-valent pneumococcal conjugate vaccine (20vPnC) (intramuscular)
20-valent pneumococcal conjugate vaccine (20vPnC)
Biological: 20-valent pneumococcal conjugate vaccine (20vPnC)
20-valent pneumococcal conjugate vaccine (20vPnC)
Other Names:
  • Prevnar 20

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Percentage of participants reporting local reactions within 7 days after each dose
Time Frame: Day 7
Prompted local reactions after each dose
Day 7
Percentage of participants reporting serious adverse events (SAEs)
Time Frame: Dose 1 to 6 months after Dose 4
SAEs occurring from Dose 1 to 6 months after Dose 4
Dose 1 to 6 months after Dose 4
Percentage of participants reporting systemic events within 7 days after each dose
Time Frame: Day 7
Prompted systemic events after each dose
Day 7
Percentage of participants reporting adverse events (AEs) from Dose 1 to 1 month after Dose 3
Time Frame: Dose 1 to 1 month after Dose 3
AEs occurring from Dose 1 to 1 month after Dose 3
Dose 1 to 1 month after Dose 3
Percentage of participants reporting AEs from Dose 4 to 1 month after Dose 4
Time Frame: Dose 4 to 1 month after Dose 4
AEs occurring from Dose 4 to 1 month after Dose 4
Dose 4 to 1 month after Dose 4

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Pfizer

Investigators

  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 4, 2026

Primary Completion (Estimated)

December 30, 2028

Study Completion (Estimated)

December 30, 2028

Study Registration Dates

First Submitted

April 30, 2026

First Submitted That Met QC Criteria

April 30, 2026

First Posted (Actual)

May 7, 2026

Study Record Updates

Last Update Posted (Actual)

May 27, 2026

Last Update Submitted That Met QC Criteria

May 26, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • C4931007
  • 2025-523447-35-00 (Registry Identifier: CTIS (EU))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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