Vaccines Against Pneumococcal Meningitis Work but Require Further Vigilance

Pneumococcal conjugate vaccines (PCVs) are proving their worth against meningitis. However, new surveillance data from Taiwan and India reveal that serotype replacement is quietly reshaping the landscape of pediatric meningitis threats, raising urgent questions about whether current vaccine formulations can keep pace, according to authors of studies published in the Journal of Infection and Public Health as well as The Lancet.^1,2

“In 2021, the new PCVs (PCV15 and PCV20) were first licensed by the FDA and recommended by the Advisory Committee on Immunization Practices (ACIP) for use in adults. PCV15 and PCV20 were approved for use in children in 2022 and 2023, respectively,” wrote the authors of a separate study in Clinical Microbiology Reviews.³ “PCV15 includes the PCV13 types and serotypes 22F and 33F, and PCV20 includes the PCV15 types and serotypes 8, 10A, 11A, 12F, and 15B. Furthermore, additional PCVs are currently available or being developed in many countries, including another 10-valent PCV (Pneumosil) in India with a unique serotype composition.”

In Taiwan, a 17-year retrospective cohort study at a major tertiary center highlighted a dramatic shift in the epidemiology of pneumococcal meningitis following the 2015 inclusion of PCV13 into the national immunization program. Although vaccine serotypes were predominant in children before 2014, the investigators found that from 2015 onwards, every identified isolate in pediatric meningitis cases belonged to nonvaccine serotypes (NVTs), such as 15A, 15B/C, 23A, 22F, 34, and 20.¹

This temporal shift also appeared to provide indirect herd protection for adults. As vaccine-type strains declined in children, a concurrent reduction was noted in the adult cohort. However, the reappearance of invasive disease driven by NVTs between 2023 and 2025 emphasizes that the population remains vulnerable to replacement strains that thrive in the empty ecological niche left by targeted serotypes.^1,4

READ MORE: Standard Pneumococcal Vaccine Schedules Are Suboptimal for High-Risk Children

Similar trends have emerged in India, where a large sentinel pediatric meningitis surveillance network assessed the impact of transitioning from targeted PCV13 use to the nationwide rollout of the 10-valent PCV10-SII (Pneumosil).²

The study found that although the proportion of children hospitalized with pneumococcal meningitis decreased, the relative frequency of NVTs increased significantly. Notably, serotype 18C, which is not included in the PCV10-SII formulation, remains a critical cause of meningitis in the region, underscoring the necessity for continued surveillance to determine if vaccine reformulations are required.

For pharmacists, these shifting serotype patterns have direct implications for clinical management and empiric therapy. In the Taiwan cohort, 100% of pediatric isolates were resistant to penicillin, and 73% were resistant to ceftriaxone.¹

These findings align with recent insights from the University of Connecticut, which note that although amoxicillin or ampicillin may suffice for pneumonia, neither penicillin nor ceftriaxone should be relied upon alone for empiric meningitis treatment. Instead, the current recommendation for suspected pediatric pneumococcal meningitis remains a combination of vancomycin and ceftriaxone.^1,5

Pharmacists must stay informed regarding local resistance patterns, as emerging NVTs like 15A and 15B/C are increasingly associated with multidrug resistance in global surveillance studies.¹

The broader scientific landscape is further complicated by the discovery of over 100 different capsular serotypes, with 107 identified as of 2024. New capsule types continue to be discovered, sometimes arising through interspecies recombination with commensal streptococci that reside in the upper respiratory tract.³

This complex landscape of updated vaccines involves significant policy deliberations regarding serotype coverage, immunogenicity, and cost. Although higher-valent vaccines like PCV20 and PCV21 offer broader protection, increasing the number of serotypes can sometimes decrease overall immunogenicity, a trade-off that requires careful monitoring in clinical settings.⁴

Although the economic burden of PCV introduction is significant, particularly in low- and middle-income countries, systematic reviews of economic evaluations suggest an incremental net monetary benefit for higher-valent vaccines.^2,6

As newer formulations like PCV15 and PCV20 become standard, the role of the pharmacist in advocating for vaccination and ensuring appropriate antimicrobial stewardship becomes even more vital. Continual monitoring of colonization and disease patterns is the only way to ensure that these lifesaving tools are used optimally and updated to meet the evolving challenge of pneumococcus.^3-5

“This study demonstrated a clear serotype replacement pattern in pneumococcal meningitis in Taiwan following PCV13 implementation in children,” concluded the authors of the primary study.¹ “The emergence of multidrug-resistant NVTs underscores the importance of continuous surveillance and supports the use of higher-valency PCVs.”

READ MORE: Pneumococcal Resource Center

REFERENCES

1. Tang CM, Li HC, Su LH, et al. Pneumococcal meningitis in children and adults before and after implementation of PCV13 into national pediatric immunization program: a cohort study in Taiwan. J Infect Public Health. 2026;19(7):103269. doi:10.1016/j.jiph.2026.103269

2. Purushothaman GKC, Rajkumar P, Kangusamy B, et al. Pneumococcal meningitis among hospitalised children after introduction of pneumococcal conjugate vaccine in India: a sentinel hospital surveillance (2019–2022). The Lancet Regional Health - Southeast Asia. 2026;50:100790. doi:10.1016/j.lansea.2026.100790

3. Ganaie FA, Beall BW, Yu J, et al. Update on the evolving landscape of pneumococcal capsule types: new discoveries and way forward. Clin Microbiol Rev. 2025 Mar 13;38(1):e0017524. doi: 10.1128/cmr.00175-24.

4. Thindwa D, Shapiro ED, Weinberger DM. The complex landscape of updated pneumococcal conjugate vaccines. OFID. 2025;12(2):ofaf050. doi:10.1093/ofid/ofaf050

5. Girotto J. Empiric treatment of pediatric pneumococcal infections: insights from a recent study. UConn School of Pharmacy and Pharmaceutical Sciences. April 21, 2026. https://pharmacy.uconn.edu/2025/11/14/empiric-treatment-of-pediatric-pneumococcal-infections-insights-from-a-recent-study/

6. Lee H, Cho JY, Vietri J, et al. The incremental net monetary benefit of higher-valent pneumococcal conjugate vaccines for adults: a systematic review and meta-analysis of economic evaluations. J Med Econ. 2025;28(1):1761-1778. doi:10.1080/13696998.2025.2565902