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Updated: Jan 19, 2026
Experimental Human Pneumococcal Carriage
Published on: February 15, 2013
Phase 1 trial of a 20-valent pneumococcal conjugate vaccine in healthy adults
Allison Thompson1, Erik Lamberth2, Joseph Severs1
1Vaccine Research and Development, Pfizer, Inc., Pearl River, NY, United States.
Insights
A new 20-valent pneumococcal conjugate vaccine (PCV20) demonstrated good safety and induced strong immune responses against 20 Streptococcus pneumoniae serotypes in adults. This vaccine offers expanded coverage to combat pneumococcal disease.
Area of Science:
- Immunology
- Vaccinology
- Infectious Diseases
Background:
- Streptococcus pneumoniae causes severe diseases like meningitis and pneumonia, particularly in young children and older adults.
- Current pneumococcal conjugate vaccines (PCV7, PCV10, PCV13) have reduced disease burden but expanded serotype coverage is needed.
- PCV20 includes serotypes from PCV13 plus seven additional serotypes associated with pneumococcal disease.
Purpose of the Study:
- To evaluate the safety, tolerability, and immunogenicity of a novel 20-valent pneumococcal conjugate vaccine (PCV20) in healthy adults.
- To compare PCV20 against a licensed tetanus, diphtheria, acellular pertussis (Tdap) vaccine control.
- To assess immune responses, including IgG and opsonophagocytic activity (OPA) titers, to all 20 serotypes in PCV20.
Main Methods:
- Phase I, randomized, controlled, observer-blinded, two-arm study in 66 healthy adults (18-49 years) with no prior pneumococcal vaccination.
- Participants received a single dose of either PCV20 or Tdap.
- Safety assessments included local reactions, systemic symptoms, and laboratory tests. Immunogenicity was measured by IgG concentrations and OPA titers pre- and post-vaccination.
Main Results:
- PCV20 vaccination induced significant increases in IgG geometric mean concentrations and OPA geometric mean titers against all 20 vaccine serotypes.
- The safety profile of PCV20 was comparable to the Tdap control and consistent with previous PCV13 data.
- No safety concerns were identified in this Phase 1 study.
Conclusions:
- PCV20 was well-tolerated in healthy adults, eliciting substantial functional (OPA) and IgG immune responses to all 20 serotypes.
- The safety and immunogenicity data support further clinical evaluation of PCV20.
- PCV20 represents a promising advancement in expanding protection against pneumococcal disease.
Introduction:
Streptococcus pneumoniae is a leading cause of bacteremia, bacterial pneumonia, and meningitis, and is associated with substantial morbidity and mortality, particularly in those under 2 years of age and those over 65 years of age. While significant progress against S. pneumoniae-related disease has been made as a result of the introduction of pneumococcal conjugate vaccines (PCV7, PCV10 and PCV13), there remains value in further expanding pneumococcal vaccine serotype coverage. Here we present the first report of a 20-valent pneumococcal conjugate vaccine (PCV20) containing capsular polysaccharide conjugates present in PCV13 as well as 7 new serotypes (8, 10A, 11A, 12F, 15B, 22F, and 33F) which are important contributors to pneumococcal disease.
Methods:
This Phase I first-in-human study was a randomized, controlled, observer-blinded study with a two-arm parallel design to assess the safety, tolerability, and immunogenicity of PCV20 in adults. A total of 66 healthy adults 18-49 years of age with no history of pneumococcal vaccination were enrolled and randomized to receive a single dose of PCV20 or a licensed tetanus, diphtheria, acellular pertussis combination vaccine (Tdap) control. Local injection site reactions, select systemic symptoms, laboratory studies, and adverse events were assessed. Opsonophagocytic activity (OPA) titers and IgG concentrations were measured in sera collected prior to, and approximately one month (28-35 days) after vaccination.
Results:
Vaccination with PCV20 elicited substantial IgG and functional bactericidal immune responses as demonstrated by increases in IgG geometric mean concentrations (GMCs) and OPA geometric mean titers (GMTs) to the 20 vaccine serotypes. The overall safety profile of PCV20 was similar to Tdap, and generally consistent with that observed after PCV13 administration.
Conclusions:
Vaccination with PCV20 was well tolerated and induced substantial functional (OPA) and IgG responses to all vaccine serotypes. There were no safety issues identified in this Phase 1 study, and the data supported further evaluation of PCV20.
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