Induction of Cross-protective Antibodies for Serogroup 33 by Pneumococcal Conjugate Vaccines (Group 33/PCVs)

May 4, 2026 updated by: David Lafon, University of Alabama at Birmingham

Novel Serotype Alert: Investigate New Pneumococcal Conjugate Vaccines for Inducing Cross-protection Against Newly Discovered Serotype 33E and Putative Novel Serogroup 33 Serotypes

The goal of this study is to learn whether different types of vaccines to prevent bacterial infections are able to effectively create antibodies that defend against certain types of bacteria.

We will give two different types of vaccine and evaluate the effectiveness of antibodies produced by each vaccine in killing bacteria.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

70

Phase

  • Phase 4

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
    • Alabama
      • Birmingham, Alabama, United States, 35294
        • Recruiting
        • University of Alabama at Birmingham
        • Principal Investigator:
          • David C LaFon, MD
        • Contact:

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Healthy adult

Exclusion Criteria:

  • No prior history of pneumococcal vaccination
  • No immunosuppressing medications or chronic diseases that affect immune function

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: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: PCV20
Will receive PCV20
Biological: Pneumococcal Vaccine
PCV
Experimental: PCV21
Will receive PCV21
Biological: Pneumococcal Vaccine
PCV

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Serogroup 33 antibodies
Time Frame: 4 weeks post-vaccination
Serum antipneumococcal antibody concentrations (micrograms/mL) against members of serogroup 33, measured using WHO-ELISA
4 weeks post-vaccination
Antibody-mediated killing
Time Frame: 4 weeks post-vaccination
Opsonic activity of vaccine-induced antibodies (reported as opsonic index, or OI); measured using an opsonophagocytic killing (OPK) assay.
4 weeks post-vaccination

Collaborators and Investigators

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

Sponsor

University of Alabama at Birmingham

Collaborators

Merck Sharp & Dohme LLC

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 (Estimated)

May 1, 2026

Primary Completion (Estimated)

March 1, 2027

Study Completion (Estimated)

August 1, 2027

Study Registration Dates

First Submitted

August 14, 2025

First Submitted That Met QC Criteria

August 20, 2025

First Posted (Actual)

August 22, 2025

Study Record Updates

Last Update Posted (Actual)

May 5, 2026

Last Update Submitted That Met QC Criteria

May 4, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IRB300008528(000544386)
  • MISP102547 (Other Grant/Funding Number: Merck Corporation)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

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.

Clinical Trials on Pneumococcal Disease

Clinical Trials on Pneumococcal Vaccine

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Israel

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe