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Optimizing Pneumococcal Vaccine Recommendations
Pneumococcal Vaccination: A Global Challenge in Coverage and Serotype Protection

Released: December 23, 2024

Expiration: December 22, 2025

Elisabeth Botelho-Nevers
Elisabeth Botelho-Nevers, MD, PhD, HDR
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Key Takeaways
  • Emerging data from ID Week 2024 highlight the need for pneumococcal vaccines with broader serotype coverage, as invasive pneumococcal disease persists, even among people fully immunized with PCV13.
  • Surveillance of pneumococcal serotype distribution is essential for guiding optimal vaccine recommendations, such as PCV20 and PCV21, based on local epidemiology patterns.
  • Low pneumococcal vaccination rates, especially in adults, highlight the need for improved strategies to enhance vaccine uptake and for increased healthcare professional recommendations.

Surveillance of pneumococcal serotype distribution and epidemiology is strongly recommended following the introduction of pneumococcal conjugate vaccines (PCVs). Although data from many countries and diverse populations are available, ongoing research continues to provide insights into the serotypes responsible for invasive pneumococcal diseases (IPD). These findings are important for tailoring recommendations for PCVs, such as the 20-valent (PCV20) or 21-valent (PCV21) vaccines, based on local epidemiologic patterns.

Immunization Impact on Serotype Distribution of Invasive Pneumococcal Disease
At ID Week 2024, Dr DJ Nieves presented findings from a prospective, countywide surveillance study of pediatric IPD and associated serotypes from 2010 to 2023. This study included 261 pediatric participants with a median age of 3.7 years. The primary clinical presentations of IPD were pneumonia (n = 102), bacteremia without a focal source (n = 100), and meningitis (n = 37).

Among 225 serotypes analyzed, 66% were serotypes not covered by the 13-valent PCV13 vaccine. Of these, serotypes covered by the 15-valent and 20-valent vaccines accounted for 19% and 47%, respectively. Of note, 6 fully immunized children with PCV13 developed meningitis due to nonvaccine serotypes and 2 of these cases were fatal. These findings highlight the persistent burden of IPD, even among children fully vaccinated with PCV13, and show the necessity of broader serotype coverage with newer vaccines.

Real-world Impact of PCV on Vaccine Serotypes and Potential Cross-reacting Nonvaccine Serotypes
A poster presented by Apodaca and colleagues further highlighted the importance of serotype surveillance. Their study investigated the real-world impact of PCV on vaccine-type serotypes. Using data from 11 countries that had implemented PCV10 or PCV13 in their pediatric national immunization programs, the study analyzed annual serotype-specific IPD cases in children younger than 5 years of age, covering a timeline from at least 1 year before vaccine introduction to 2019.

The results demonstrated significant reductions in vaccine-type IPD cases across all countries following PCV introduction. However, some cases caused by vaccine-related serotypes, such as serotype 6B (where serotype 6A is the vaccine serotype), either remained stable or increased. These observations suggest variability in cross-protection against vaccine-related serotypes depending on the vaccine used, a phenomenon that requires further investigation. This variability has important implications for disease trends and must be carefully considered when evaluating pneumococcal vaccination programs.

Uptake of Pneumococcal Vaccination After IPD in Italy
Lastly, Giacomo and colleagues presented a poster examining pneumococcal vaccination updates following episodes of IPD in 2 centers in northern Italy. This research addresses the global challenge of low adult pneumococcal vaccine coverage and the frequent missed opportunities for vaccination.

The retrospective study included people aged 18 years or older with positive blood or cerebrospinal fluid cultures for Streptococcus pneumoniae between January 1, 2015, and December 31, 2019, with follow-up data collected until March 31, 2024. Vaccination records were retrieved from the Italian National Vaccination Portal (SIAVR).

The study included 211 people, with a median age of 69.6 (range, 59.0-78.5), 56.4% of whom were male. The median Charlson Comorbidity Index was 5 (range, 3-6). At admission, only 4.3% (n = 7) had been vaccinated against pneumococcus, with 5 receiving a single dose and 2 completing the PCV13 and PPSV23 series.

At discharge, vaccination uptake was low, with only 22% of people (n = 47) receiving a vaccination. One explanation for this low vaccination rate may be that, at discharge, vaccination recommendations were provided to only 12.3% of people (n = 26). The authors concluded that people who were provided with a vaccination recommendation were more likely to receive the vaccination (34% [n=16] vs 6.1% [n=10], P <.001).

Among vaccinated participants, the median time to vaccination was 6.6 months (range, 2.3-29.9) after the infection, leaving them vulnerable to recurrent infection during this period.

The authors concluded that pneumococcal vaccination uptake was suboptimal in their cohort of adults presenting with IPD. They highlighted the inadequate frequency of vaccination recommendations at discharge and the need to strengthen a stronger prevention culture among both patients and healthcare professionals. Unfortunately, this issue reflects a broader global issue.

Conclusion
These findings demonstrate that although surveillance of serotype distribution can help with the optimal selection of PCV, vaccination coverage remains low, even among patients with prior episodes of IPD. Substantial improvements are needed to ensure that the demonstrated efficacy of pneumococcal vaccines translates into real-world protection. Efforts to enhance vaccination practices must be prioritized to safeguard patients from pneumococcal disease recurrence.

Your Thoughts?
What strategies would you prioritize to address gaps in vaccine uptake and ensure broader serotype coverage? Join the conversation by posting a comment below.