What is the difference between Pneumococcal Conjugate Vaccine (PCV) 15, PCV 13, and PCV 23?

Differences Between PCV15, PCV13, and PPSV23 (PCV23)

The primary difference between pneumococcal vaccines is their serotype coverage and mechanism of action: PCV15 contains 15 serotypes (13 from PCV13 plus 2 additional), PCV20 contains 20 serotypes (all 13 from PCV13 plus 7 additional), and PPSV23 contains 23 serotypes but uses a different immune mechanism that may be less effective in certain populations. 1

Serotype Coverage

• PCV13 contains 13 pneumococcal serotypes conjugated to CRM197 carrier protein 1
• PCV15 contains all 13 serotypes from PCV13 plus two additional serotypes (22F and 33F), also conjugated to CRM197 carrier protein 1
• PPSV23 (commonly referred to as PCV23) contains 23 pneumococcal polysaccharide serotypes without conjugation to a carrier protein 1

Vaccine Composition and Mechanism

• Conjugate vaccines (PCV13, PCV15, PCV20): Polysaccharide antigens are chemically linked to a carrier protein (CRM197), inducing a T-cell dependent immune response that creates memory B-cells, providing potentially longer-lasting immunity 1
• Polysaccharide vaccine (PPSV23): Contains purified capsular polysaccharide antigens that induce a T-cell independent immune response, which does not result in memory B-cell creation, potentially leading to shorter duration of protection 1

Immunogenicity Differences

• PCV15 demonstrated noninferiority to PCV13 for the 13 shared serotypes and showed statistically higher immune responses for serotype 3 and the PCV15-unique serotypes 22F and 33F 1
• PCV15 induced numerically higher IgG GMCs and OPA GMTs for 8 of 13 and 7 of 13 shared serotypes compared to PCV13, respectively 1
• When comparing PCV15 to PPSV23, noninferiority was met for all 14 shared serotypes, with IgG GMC and OPA GMTs numerically higher for 13 of 14 serotypes (except for serotype 19F) 1
• In adults who received PCV15 followed by PPSV23, immune responses were generally comparable to those who received PCV13 followed by PPSV23 1

Safety Profile

• All pneumococcal vaccines have similar safety profiles with primarily mild side effects 2
• Most common adverse reactions for all vaccines include:
  • Injection site pain, erythema (redness), and swelling 2
  • Systemic reactions such as fatigue, myalgia, and fever 1, 2
• Serious adverse events are rare for all pneumococcal vaccines 2
• In clinical trials, the rates of serious adverse events within 6 months were similar between PCV15 (2.5%) and PCV13 (2.4%) recipients 1

Clinical Implications and Recommendations

• The Advisory Committee on Immunization Practices (ACIP) now recommends either PCV20 alone or PCV15 followed by PPSV23 for adults ≥65 years and adults 19-64 years with certain underlying medical conditions 3
• For adults who previously received PPSV23 only, a single dose of either PCV20 or PCV15 is recommended ≥1 year after the last PPSV23 dose 1
• When PCV15 is used, the recommended interval between PCV15 and PPSV23 is ≥1 year for most adults, but a minimum interval of 8 weeks can be considered for adults with immunocompromising conditions, CSF leaks, or cochlear implants 1

Special Considerations

• PCV15 has shown similar or higher immune responses compared to PCV13 in adults ≥65 years who previously received PPSV23 1, 4
• In healthy adults 18-49 years, PCV13 and PCV15 induced similar serotype-specific responses for all shared serotypes, including functional antibody responses against serotype 3 5
• Matching-adjusted indirect comparison studies suggest PCV15 may be non-inferior to PCV20 for all PCV13 serotypes and potentially superior for five serotypes (3, 6A, 6B, 18C, and 23F) 6

Clinical Decision-Making Algorithm

1. For pneumococcal vaccine-naïve adults:

   • Use either PCV20 alone or PCV15 followed by PPSV23 (≥1 year later for immunocompetent adults; ≥8 weeks later for immunocompromised) 1, 3

2. For adults who previously received PPSV23 only:

   • Administer either PCV20 or PCV15 ≥1 year after the last PPSV23 dose 1

3. For adults who previously received PCV13:

   • If aged 19-64 years with chronic medical conditions: Administer either PCV20 or PPSV23 ≥1 year after PCV13 1
   • Reassess recommendations when the person turns 65 years 1