Introduction of PCV10 Reduces Pneumococcal Infections for Children

Pneumococcal infections were significantly reduced among children in the first 3 years of Poland introducing the 10-valent pneumococcal conjugate vaccine (PCV10) to its National Immunization Program (NIP), according to a study published in Vaccine.¹

Despite PCV10 vaccine-type (VT) strains decreasing significantly, results from the study highlight the important need for public health officials to continuously monitor the evolution of Streptococcus pneumoniae (S. pneumoniae) infections.

“S. pneumoniae, despite the availability of vaccines, was globally responsible for 300,000 deaths of children under 5 years of age in 2015. The primary virulence determinant of S. pneumoniae is its polysaccharide capsule,” wrote the authors of the study.¹ “Based on its composition, more than 100 serotypes have been distinguished so far. Capsular polysaccharides are widely studied due to a fact that they are used as antigens in all current pneumococcal vaccines.”

According to authors of a study published in Microbiology Spectrum, polysaccharide capsules are the dominant surface structures for S. pneumoniae organisms.² As various valencies are added to PCVs as they are developed, the composition for all vaccines approved against pneumococcal infections relies on these capsular polysaccharides.

READ MORE: Pneumococcal Conjugate Vaccine Booster Maximizes Protection Against IPD

The vaccines available in the US for protection against S. pneumoniae include PCV21 (Capvaxive); PCV20 (Prevnar20); PCV15 (Vaxneuvance); and the pneumococcal polysaccharide vaccine, or PPSV23 (Pneumovax 23).³ However, as previously mentioned, higher valencies are needed throughout the development of vaccines to protect against various vaccine and nonvaccine serotypes (NVTs). Furthermore, in Poland, where the study was conducted, PCV10 has been the key approach for protecting children against pneumococcal infections.

“PCV10 (Synflorix) and PCV13 (Prevenar 13) have been available in Poland since 2009 and 2010, respectively,” continued the authors.¹ “PCV was included in the NIP as mandatory for all children born after December 31, 2016. To date, PCV10 has consistently been the vaccine of choice in all NIP tenders except for one in 2022.”

With a specific focus on invasive pneumococcal disease (IPD) among children, researchers stated the significant importance of monitoring pneumococcal infections because of their potential impacts on youth populations. Subsequently, the need to stay alert to pneumococcal infections and their epidemiology is assisted through understanding specific trends following vaccine implementation.

The researchers set out to investigate the changes in population and genetic composition of pneumococcal strains that cause IPD among children under 2 years old in Poland.

“This study included all invasive pneumococcal isolates from children under 2 years of age collected during nationwide voluntary based laboratory surveillance of IPD in Poland conducted by the National Reference Centre for Bacterial Meningitis between 2014 and 2020,” they wrote.¹ “The collection included 2 groups based on the time of isolation: isolates collected before the introduction of mandatory pneumococcal vaccination (the pre-PCV period, years 2014-2016) and isolates collected after the introduction (the post-PCV period, years 2017-2020).”

The investigators used standard laboratory methods to identify, serotype, and test pneumococcal isolates. S. pneumoniae isolates experienced full genome sequencing so researchers could understand the general impacts of PCV10 since 2016.

Among all the pneumococci explored, researchers uncovered a total of 207 serotypes throughout the study period. The pre-PCV period from 2014 to 2016 included 102 serotypes, while the post-PCV period recorded 105. Due to the introduction of PCV10 in the Poland NIP, PCV10-VT strains decreased from 56.9% to 29.5% throughout the study period. Serotypes that were most prevalent in higher-valency vaccines, however, increased—albeit modestly—from 17.6% to 25.7%. NVTs also increased from 12.8% to 22.9%.

“As expected, we observed a decrease in PCV10-VT, similar to other countries that use PCV10 in their NIPs,” continued the authors of the study.¹ “However, PCV10-VT isolates were still found in the post-PCV period.”

The key reason for PCV10-VT isolates appearing in the post-PCV period, as researchers expected, was due to the potential of children being born before the widespread implementation of PCV10 or if they did not complete the vaccine schedule once they contracted IPD.

Furthermore highlighting PCV10’s success, investigators also discovered significant decreases in antimicrobial as well as multidrug resistance. Indeed, they reported significant decreases in patients’ resistance to penicillin, erythromycin, clindamycin, and chloramphenicol. Among the findings regarding PCV10’s efficacy, as well as the NVT and VT strains further identified, researchers believe this study can make a significant impact across various NIPs around the world.

“Our findings indicate a significant reduction in PCV10-VT strains, along with a decrease in antibiotic resistance and the prevalence of piliated isolates,” they concluded.¹ “Concurrently, we noted an increase in PCV10-NVTs, which are encompassed within higher-valent vaccines as well as those not covered by any available pneumococcal vaccines. We are convinced that, despite inherent limitations, the results derived from national surveillance of IPD provide invaluable information for policymakers regarding the potential implementation of higher-valent vaccines.”

READ MORE: Pneumococcal Resource Center

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REFERENCES

1. Wróbel-Pawelczyk I, Gołębiewska A, Ronkiewicz P, et al. Changes in the Streptococcus pneumoniae population responsible for invasive disease of young children after the implementation of conjugated vaccines in the National Immunization Program in Poland. Vaccine. 2025;64:127759. https://doi.org/10.1016/j.vaccine.2025.127759

2. Paton JC, Trappetti C. Streptococcus pneumoniae capsular polysaccharide. Microbiol Spectr. 2019 Mar;7(2):10.1128/microbiolspec.gpp3-0019-2018. doi: 10.1128/microbiolspec.GPP3-0019-2018.

3. About pneumococcal vaccines. CDC. September 11, 2024. Accessed October 15, 2025. https://www.cdc.gov/vaccines/vpd/pneumo/hcp/about-vaccine.html