Last reviewed 2026-04-22 · How we verify

23vPS

23vPS is a 23-valent pneumococcal polysaccharide vaccine that stimulates the immune system to produce antibodies against 23 serotypes of Streptococcus pneumoniae.

23vPS is a 23-valent pneumococcal polysaccharide vaccine that stimulates the immune system to produce antibodies against 23 serotypes of Streptococcus pneumoniae. Used for Prevention of invasive pneumococcal disease in adults and children ≥2 years of age, Prevention of pneumococcal pneumonia.

At a glance

Mechanism of action

The vaccine contains purified capsular polysaccharides from 23 different serotypes of pneumococcus conjugated to a protein carrier or presented as unconjugated polysaccharides. Upon administration, these antigens trigger B-cell and T-cell responses, leading to the production of opsonizing antibodies that enhance phagocytosis and clearance of pneumococcal bacteria. This provides protection against invasive pneumococcal disease and pneumococcal pneumonia caused by the included serotypes.

Approved indications

• Prevention of invasive pneumococcal disease in adults and children ≥2 years of age
• Prevention of pneumococcal pneumonia

Common side effects

• Injection site pain, erythema, or swelling
• Fever
• Myalgia or arthralgia
• Headache
• Fatigue

Key clinical trials

• Study Comparing a 13-valent Pneumococcal Conjugate Vaccine With 23-valent Pneumococcal Polysaccharide Vaccine in Adults (PHASE3)
• Study to Evaluate 13 Valent Pneumococcal Conjugate Vaccine (13vPnC) Vaccine Followed by 23-valent Pneumococcal Polysaccharide Vaccine (23vPS) Vaccine in Allogeneic Hematopoietic Stem Cell Transplant Recipients (PHASE3)
• Concomitant Administration of 13-valent Pneumococcal Conjugate Vaccine (13vPnC) With Influenza Vaccine in 23-valent Pneumococcal Polysaccharide (23vPS) Pre-vaccinated Adults. (PHASE4)
• Study Immunogenicity and Safety of 13-valent Pneumococcal Conjugate Vaccine (PHASE3)
• Safety and Immunogenicity of 13-Valent Pneumococcal Conjugate Vaccine (13vPnC) in HIV-Infected Subjects 6 Years of Age or Older Who Are Naive to Pneumococcal Vaccine (PHASE3)
• Study Evaluating 13-valent Pneumococcal Conjugate Vaccine (13vPnC) in Children With Sickle Cell Disease (PHASE3)
• A Phase 3 Trial Evaluating the Safety, Tolerability, and Immunogenicity of a 13-valent Pneumococcal Conjugate Vaccine in Japanese Elderly Adults Aged 65 Years Old and Older (PHASE3)
• Safety & Immunogenicity of 13vPnC in HIV-Infected Subjects Aged 18 or Older Who Were Previously Immunized With 23vPS (PHASE3)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.