Pneumococcal Vaccine Effectiveness in Adults Over 50 Years
Pneumococcal vaccines are highly effective in adults over 50 years old, with the newer conjugate vaccines (PCV13, PCV15, PCV20) demonstrating superior effectiveness compared to PPSV23, particularly when given as the initial vaccine. 1, 2
Vaccine Effectiveness Data
PCV13 Efficacy in Older Adults
PCV13 demonstrated 45.6% efficacy against vaccine-type community-acquired pneumonia, 45.0% efficacy against vaccine-type non-bacteremic pneumonia, and 75.0% efficacy against vaccine-type invasive pneumococcal disease in adults ≥65 years in the landmark CAPiTA trial involving over 84,000 participants. 3
PCV13 has well-established immunogenicity and tolerability in adults ≥50 years of age, with robust immune responses documented across multiple studies. 3
PPSV23 Effectiveness
PPSV23 shows modest effectiveness of 48% against all pneumococcal pneumonia in adults over 50 years, with higher effectiveness against bacteremic disease (66% effectiveness) compared to non-bacteremic pneumonia (42% effectiveness). 4
PPSV23 effectiveness is highest against bacteremic infections caused by vaccine-type serotypes (76% effectiveness). 4
Sequential Vaccination Strategy
Sequential PCV13 followed by PPSV23 demonstrates the highest effectiveness of 80.3% against pneumococcal pneumonia in adults aged 65-74 years, significantly outperforming either vaccine alone. 5
Single-dose PCV13 alone showed 66.4% effectiveness in the 65-74 age group, while PPSV23 alone showed only 18.5% effectiveness (not statistically significant). 5
In adults ≥75 years, vaccine effectiveness was lower and not statistically significant for any regimen, suggesting age-related decline in vaccine response. 5
Current Vaccination Recommendations
Age-Based Recommendations
All adults aged ≥50 years who have never received a pneumococcal conjugate vaccine should receive a single dose of PCV20 or PCV21 as the preferred option. 2
Alternatively, adults can receive PCV15 followed by PPSV23 at least 1 year later. 1, 2
Risk-Based Vaccination for Ages 50-64
Adults aged 50-64 years with chronic medical conditions (diabetes, heart disease, COPD, chronic liver disease, alcoholism) should receive PCV20 immediately. 6, 7
Adults with immunocompromising conditions, functional or anatomic asplenia, cerebrospinal fluid leak, or cochlear implants should receive PCV20 regardless of age. 6, 7
Current smokers and residents of long-term care facilities should receive PCV20. 6
Immunologic Superiority of Conjugate Vaccines
T-Cell Dependent Immunity
PCV vaccines induce T-cell dependent immune responses that provide immunologic memory and sustained protection with repeat vaccination, unlike PPSV23 which induces only T-cell independent responses. 8
A second dose of PCV13 given approximately 4 years after initial vaccination induced significantly higher antibody responses for 7 of 13 serotypes compared to the initial vaccination. 8
In contrast, revaccination with PPSV23 resulted in significantly lower antibody responses for 9 of 13 serotypes compared to initial PPSV23, demonstrating hyporesponsiveness. 8
Priming Effect
Initial vaccination with PCV13 establishes immune memory that results in superior recall responses upon subsequent vaccination with either PCV or PPSV23. 8
Adults who received PPSV23 after initial PCV13 had significantly higher antibody responses for 10 of 13 serotypes compared to those who received PPSV23 as their first vaccine. 8
Clinical Guidance for Previously Vaccinated Adults
For Adults Who Received PPSV23 Only
- Adults who previously received only PPSV23 should receive a single dose of PCV20 or PCV15 at least 1 year after the last PPSV23 dose. 1, 6
For Adults Who Received PCV13 Only
- Adults who previously received only PCV13 should receive PCV20 after at least a 1-year interval. 1, 6
For Adults Who Completed PCV13 and PPSV23 Series
- Shared clinical decision-making is recommended regarding use of a supplemental PCV20 dose for adults ≥65 years who have completed their series with both PCV13 and PPSV23. 1
Important Caveats
Age-Related Decline in Effectiveness
- Vaccine effectiveness appears to decline with advancing age, with significantly lower effectiveness observed in adults ≥75 years compared to those aged 65-74 years. 5
Serotype Coverage
During 2018-2019, approximately 60-75% of all invasive pneumococcal disease in adults was caused by serotypes included in current vaccines (PCV13, PCV15, PCV20, PPSV23). 1
The remaining 25-40% of disease is caused by non-vaccine serotypes, limiting overall vaccine impact. 1