Pneumococcal Vaccine: Are You Fully Protected?
"A new study reveals a surprising gap in pneumococcal vaccination rates among older adults, highlighting the need for better awareness and adherence to recommended guidelines."
Pneumonia, often caused by the bacterium Streptococcus pneumoniae, poses a significant threat to older adults. This infection can lead to serious conditions, including invasive pneumococcal diseases (IPD), resulting in high morbidity, mortality, and healthcare costs. Vaccination is a key preventive measure, yet recent research suggests that many older adults may not be fully protected.
Two pneumococcal vaccines are currently licensed in the United States: pneumococcal conjugate vaccine (PCV13) and pneumococcal polysaccharide vaccine (PPV23). These vaccines protect against different serotypes of the bacteria, and since 2014, the Advisory Committee on Immunization Practices (ACIP) has recommended a sequential approach – PCV13 followed by PPV23 – for adults 65 and older.
A new study published in Vaccine examines pneumococcal vaccination patterns among adults aged 65 years or older in the United States. Using a large claims database, the researchers investigated vaccination rates, completion of the recommended series, time between doses, and factors associated with series completion. The findings reveal a concerning gap in adherence to vaccination guidelines, underscoring the need for improved strategies to protect this vulnerable population.
Current Coverage and Impact
In 2024, 25.1% of U.S. adults aged 18 and older reported ever receiving a pneumococcal vaccination. During a 21-month follow-up period after 2022, 13.2% of adults, or 6.8 million people, received a pneumococcal vaccine; 9.6% received PCV20. CDC data also show that invasive pneumococcal disease rates in the United States decreased dramatically after pneumococcal conjugate vaccines were introduced. Global coverage data are reported annually through the WHO/UNICEF Joint Reporting Form on Immunization.
Recommendations and Measurement Limits
The CDC summarizes current pneumococcal vaccination recommendations according to age and risk. Recent reviews describe PCV20 and emerging PCV21 candidates as part of an evolving vaccine landscape, while noting that serotype replacement remains an ongoing challenge. Conjugate vaccines have reduced invasive pneumococcal disease and provided herd-immunity benefits, but those gains do not eliminate replacement by other serotypes. Assessing protection is also difficult because antibody assays show interlaboratory variability and lack standardized protective thresholds.
A Century of Vaccine Development
The history of pneumococcal vaccination spans more than a century of vaccine strategies, with a major review examining developments and adult vaccination approaches over the past 111 years. During the 1918 to 1919 influenza pandemic and the First World War, researchers administered a trivalent pneumococcal vaccine to 12,519 men in training in the United States. Later efforts to expand childhood protection included a US$1.5 billion pilot Advance Market Commitment established by five countries and the Bill & Melinda Gates Foundation. Another historical account describes widespread pneumonia-vaccine use as emerging in the late 1970s, meaning the modern era of availability has lasted nearly half a century.
The Vaccination Gap: Key Findings on Pneumococcal Protection
The study, which analyzed data from over 224,000 adults, revealed that nearly half (49%) had not received any pneumococcal vaccination. Only 16.8% had completed the recommended PCV13-PPV23 series. This leaves a large proportion of older adults potentially vulnerable to pneumococcal disease.
- Low Completion Rates: Only a small percentage of older adults are completing the recommended pneumococcal vaccination series.
- Missed Opportunities: A significant number of adults are receiving only one of the two recommended vaccines, leaving them partially unprotected.
- Timing Matters: The interval between doses can vary, with some individuals not receiving the second vaccine within the recommended timeframe.
Evidence Across Age Groups
A 2025 narrative review argues that adult pneumococcal-pneumonia prevention strategies need reconsideration following the availability of PCV21 alongside PCV15 and PCV20. A systematic review and meta-analysis examined studies published from 2016 to 2019 on pneumococcal vaccination in elderly populations. Another meta-analysis assessed PCV13 and PPSV23 efficacy or effectiveness against vaccine-type disease, invasive pneumococcal disease, and pneumococcal pneumonia in adults. Separate recent research focuses on the efficacy, immunogenicity, and safety of pneumococcal vaccines for reducing serious childhood disease.
Remaining Uncertainties
Pneumococcal vaccination can reduce risk without guaranteeing that every vaccinated person will avoid infection or pneumonia. Protection may vary with the circulating serotypes, individual health factors, vaccine history, and the outcome being measured. These limitations make it important to distinguish vaccine coverage, immune response, disease prevention, and protection against severe outcomes rather than treating them as interchangeable.
Conjugate and Polysaccharide Options
The five FDA-approved pneumococcal vaccines differ in formulation and coverage. Pharmacy Times reports that newer conjugate vaccines such as PCV20 and PCV21 offer broader serotype coverage and better immune memory than the older polysaccharide vaccine, although geographic factors may influence selection. Patients who previously received PPSV23 alone may receive PCV15 or PCV20 at least one year later to complete the series, while those who received PCV13 alone or with PPSV23 should complete the previously recommended PPSV23 series. Drug Topics reports that CDC recommendations changed six times in three years as new vaccines were approved, including expansion to all adults aged 50 and older.
Protecting Our Seniors: Steps to Improve Pneumococcal Vaccination Rates
These findings underscore the urgent need to improve pneumococcal vaccination rates among older adults. Increasing awareness of the ACIP recommendations, particularly the importance of completing the PCV13-PPV23 series, is crucial.
What Current Evidence Suggests
Effective pneumococcal vaccines are available and have been used in many countries, although global programs have historically focused heavily on children. A 2026 U.S. study found that PCV20 vaccination was associated with lower risks of invasive pneumococcal disease, pneumococcal pneumonia, all-cause pneumonia, and lower respiratory tract infection among adults aged 65 years or older compared with no PCV20 vaccination. Another 2026 study reported a clinically relevant protective effect against poor outcomes among hospitalized patients with pneumococcal pneumonia after adjustment for indication bias using propensity-score matching. These findings support meaningful protection while leaving room for continued evaluation across populations and outcomes.
Expansion and Innovation
Market forecasts identify North America as a leading region for pneumococcal vaccines, with one analysis projecting a 36.1% share of the global market in 2026. Another forecast describes North America as the largest market and Asia-Pacific as the fastest-growing area. Reported drivers include technological advances intended to improve vaccine efficacy and safety, increasing geriatric populations, greater awareness of vaccine efficacy, and expanding national immunization programs. These projections describe market direction rather than guaranteed health outcomes.
Beyond Serotype Coverage
Streptococcus pneumoniae can asymptomatically colonize the nasopharynx, cause mucosal infections, or produce invasive pneumococcal disease. Recent commentary argues that the continuing disease burden reflects an inherent limitation of strategies that rely on serotype-dependent humoral immunity. PCV20 offers broader protection than earlier conjugate vaccines and may reduce invasive and noninvasive infections in children, but broader coverage does not remove every biological or implementation challenge. Researchers are also studying how serotype affects responses in adults previously given PCV13, PPV23, or placebo in the PREVENTING PNEUMO 2 challenge trial in the United Kingdom.
Real-World Evidence Can Differ
A population-based cohort study followed 2,234,003 adults in Catalonia during 2019, before the COVID-19 period. The study reported that antipneumococcal vaccination did not prove effective in preventing hospitalization or death from pneumococcal or all-cause pneumonia during that year. This result differs from evidence of benefit reported in other settings and outcomes, so it should not be generalized to every vaccine, population, or endpoint. It underscores why real-world effectiveness must be interpreted in light of study design, population characteristics, circulating disease, and the outcome measured.
Healthcare providers play a vital role in educating patients about pneumococcal disease and the benefits of vaccination. Strategies to improve vaccination rates include standing orders, reminder systems, and co-administration of pneumococcal vaccines with other recommended adult vaccines (e.g., influenza vaccine).
Further research is needed to understand the barriers to pneumococcal vaccination in specific populations and to develop targeted interventions to address these challenges. By working together, healthcare providers, public health organizations, and individuals can help protect older adults from the serious consequences of pneumococcal disease.