Pneumococcal Conjugate Vaccines (PCVs)
The pneumococcal vaccine that starts with "C" refers to pneumococcal conjugate vaccines (PCVs), which include PCV13, PCV15, PCV20, and the newest PCV21 (brand name CAPVAXIVE). 1
Current Vaccine Options Starting with "C"
The "C" stands for conjugate, distinguishing these from the polysaccharide vaccine (PPSV23). The available conjugate vaccines are:
- PCV13 (Prevnar13) - 13-valent conjugate vaccine
- PCV15 (VAXNEUVANCE) - 15-valent conjugate vaccine
- PCV20 (Prevnar20) - 20-valent conjugate vaccine
- PCV21 (CAPVAXIVE) - 21-valent conjugate vaccine 1, 2
Why "Conjugate" Matters
Conjugate vaccines link pneumococcal polysaccharides to a protein carrier (diphtheria toxoid), which:
- Generates stronger, longer-lasting immune responses
- Creates immunologic memory
- Provides superior protection compared to polysaccharide vaccines alone
- Is particularly important for immunocompromised individuals 3, 4
Current Recommendations (2024)
For adults ≥50 years who have never received a pneumococcal conjugate vaccine, a single dose of PCV20, PCV21, or PCV15 (followed by PPSV23) is now recommended. 2
Key Decision Points:
- PCV20 or PCV21 alone completes the series - no additional doses needed
- PCV15 requires PPSV23 follow-up (≥1 year later for most adults, ≥8 weeks for immunocompromised) 1
Important Caveat About PCV21
PCV21 does NOT contain serotype 4, which is present in PCV15, PCV20, and PPSV23. In western U.S. populations (particularly Alaska and Navajo Nation), serotype 4 causes ≥30% of invasive pneumococcal disease. In these high-serotype-4 areas, PCV20 may be preferred over PCV21. 1
Contraindications
All conjugate vaccines are contraindicated in persons with:
- Severe allergic reaction to any vaccine component
- Severe allergic reaction to any diphtheria toxoid-containing vaccine (specific to conjugate vaccines) 1