How pneumococcal conjugate vaccines may produce antibodies that protect against serogroup 33.

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

Phase 4 Interventional University of Alabama at Birmingham · NCT07135453

This will try two different pneumococcal conjugate vaccines in healthy adults to see which one makes antibodies that can kill serogroup 33 bacteria.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment70 (estimated)
Ages18 Years and up
SexAll
SponsorUniversity of Alabama at Birmingham Academic / other
Locations1 site (Birmingham, Alabama)
Trial IDNCT07135453 on ClinicalTrials.gov

What this trial studies

In this Phase 4, post-licensure comparison, healthy adult participants will receive one of two licensed pneumococcal conjugate vaccines and have blood drawn before and after vaccination. Laboratory assays will measure the presence and bactericidal activity of antibodies specifically against serogroup 33. Individuals with prior pneumococcal vaccination or conditions/medications that suppress immunity are excluded. The study is conducted at the University of Alabama at Birmingham in collaboration with Merck.

Who should consider this trial

Good fit: Healthy adults with no prior pneumococcal vaccination and no chronic diseases or medications that suppress the immune system are ideal candidates.

Not a fit: People who are immunocompromised, have chronic immune-impacting conditions, or who have already received a pneumococcal vaccine are unlikely to qualify or benefit from this protocol.

Why it matters

Potential benefit: If successful, the results could show that an existing pneumococcal conjugate vaccine provides cross-protection against serogroup 33 and guide vaccine choice or future vaccine design.

How similar studies have performed: Some prior work has shown pneumococcal conjugate vaccines can induce cross-reactive antibodies, but protection specifically against serogroup 33 remains uncertain.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Healthy adult

Exclusion Criteria:

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

Where this trial is running

Birmingham, Alabama

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions VaccinePneumococcal Disease
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.