PCV Remains Effective Despite Nonvaccine Serotypes Increasing

Although pneumococcal conjugate vaccines (PCVs) exhibit significant protection against invasive pneumococcal disease (IPD), continuously emerging nonvaccine serotypes (NVTs) highlight a persistent challenge for public health officials. As the development of more effective PCVs continues, researchers believe this is a necessary approach to combat new serotypes, according to JAMA Network Open.¹

“PCVs reduced the incidence rate of IPD in children, but NVTs continue to cause disease and are replacing the disease burden previously associated with serotypes covered by PCVs. Additionally, some serotypes covered by PCVs persist,” wrote the authors of the study. “The success and cost-effectiveness of PCV programs depend not only on the protection in vaccinated individuals, primarily young children, but also on providing indirect (herd) protection to unvaccinated groups, particularly adults aged 65 years and older.”

Data from the Canadian study showed that although PCV7 and PCV13 were nearly 99% effective in reducing targeted serotypes in children, overall IPD incidence rates in the general population actually increased between 2000 and 2019.¹

READ MORE: Updated Pneumococcal Vaccine Strategies Target Evolving Adult Risks

This surge was largely due to serotype replacement, a phenomenon where nonvaccine types fill the ecological void left by eliminated strains. For example, serotypes 3, 4, and 19F remained persistent in Canada despite inclusion in earlier formulations, particularly impacting adults who saw limited indirect protection from pediatric programs.

The Uniformity of Findings Across Multiple PCV-Related Studies

This clinical efficacy is mirrored in outcomes for other conditions, such as community-acquired alveolar pneumonia (CAAP), according to a study in Clinical Infectious Disease.²

The decade-long prospective study found that the PCV13 series provided up to 87.2% protection against CAAP in children aged 12 to 35 months, proving its utility against noninvasive endpoints. Such findings emphasize that although the target serotypes may shift, the underlying conjugate technology remains a potent option for reducing severe pneumococcal morbidity.

However, the threat remains dynamic because pneumococcal invasiveness—the likelihood of a strain progressing from colonization to disease—is not uniform across all serotypes. Certain NVTs like 8 and 12F possess high invasive potential, allowing them to transform from harmless nasopharyngeal colonizers into deadly pathogens, according to Drug Topics.^1,3

As these strains emerge, the development and implementation of higher-valency vaccines, like PCV15, PCV20, and PCV21, have become paramount. Canadian researchers estimated that PCV21 alone could have covered up to 49% of observed IPD isolates between 2015 and 2019.^1,3,4

Pneumococcal Vaccine Guidelines for Patients, Pharmacists

The CDC currently recommends these newer PCVs for children and adults, yet implementing these complex schedules requires high clinical literacy from healthcare providers.⁴

This is particularly vital as updated economic models evaluate the cost-effectiveness of expanding age-based recommendations to adults as young as 50 years old. In these analyses, PCV21 often demonstrates a more favorable cost-effectiveness ratio compared with other formulations due to its unique coverage of circulating NVTs, according to a 2024 report from the CDC’s Advisory Committee on Immunization Practices (ACIP).⁵

“This study highlights gaps in pharmacists’ knowledge of pneumococcal vaccine recommendations and identifies key barriers to vaccination within the community pharmacy setting,” according to US Pharmacist.⁶ “Targeted education and interventions could help address key barriers and enhance the effectiveness of community pharmacy immunization services, particularly for high-risk populations.”

For community pharmacists, who are visited more frequently than primary care physicians, this evolving landscape presents a critical opportunity to serve as public health hubs. A survey of pharmacists revealed significant knowledge gaps, with many identifying the correct pneumococcal vaccination guidelines in only 3 of 9 clinical cases.^3,6

Despite high confidence in their ability to deliver services, these gaps in understanding frequently changing recommendations can hinder effective patient advocacy. As frontline providers, pharmacists must bridge this information gap to ensure that both pediatric and adult populations receive the direct protection necessary to reduce the global burden of this unpredictable pathogen.^1,3,6

“Improving overall PCV effectiveness will require vaccinating both pediatric and adult populations, especially considering the limited indirect protection in adults,” concluded authors of the current study.¹ “Furthermore, the continuous threat of emerging NVTs causing IPD remains a significant challenge, highlighting the need for a new generation of broad-coverage vaccines.”

READ MORE: Pneumococcal Resource Center

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REFERENCES

1. Ramos B, Vadlamudi NK, Golden AR, et al. Invasive pneumococcal disease epidemiology and conjugate vaccines in Canada, 2000-2019. JAMA Netw Open. 2026;9(4):e266005. doi:10.1001/jamanetworkopen.2026.6005

2. Lewnard JA, Givon-Lavi N, Dagan R. Effectiveness of pneumococcal conjugate vaccines against community-acquired alveolar pneumonia attributable to vaccine-serotype streptococcus pneumoniae among children. Clin Infect Dis. 2021 Oct 5;73(7):e1423-e1433. doi: 10.1093/cid/ciaa1860.

3. Nowosielski B. Serotype diversity shapes the future of pneumococcal prevention. Drug Topics. May 7, 2026. Accessed May 7, 2026. http://drugtopics.com/view/serotype-diversity-shapes-the-future-of-pneumococcal-prevention

4. Types of pneumococcal vaccines. CDC. February 25, 2026. Accessed May 7, 2026. https://www.cdc.gov/pneumococcal/vaccines/types.html

5. Summary of three economic analyses on the use of PCVs among 50-64 year old adults in the United States. CDC. October 23, 2024. Accessed May 7, 2026. https://www.cdc.gov/acip/downloads/slides-2024-10-23-24/03-Leidner-Pneumococcal-508.pdf

6. How informed are community pharmacists about pneumococcal vaccines? U.S. Pharmacist. News Release. February 19, 2025. Accessed May 7, 2026. https://www.uspharmacist.com/article/how-informed-are-community-pharmacists-about-pneumococcal-vaccines