Vaccine Serotypes Reemerge in Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae has reemerged as a common pathogen among older adults, according to a prospective multicenter cohort study published in Pneumonia. Researchers with the CAPNETZ Study Group analyzed 2028 adults with all-cause CAP enrolled at 26 centers across Germany between January 1, 2020, and December 31, 2023, of whom 1504 provided urine samples for serotype-specific urine antigen detection (SSUAD) testing.¹

The findings show that vaccine-covered serotypes, especially serotype 3, continued to circulate throughout the SARS-CoV-2 pandemic and increased in prevalence among adults 60 years and older. The study aimed to determine what proportion of CAP cases in Germany could be attributed to serotypes covered by PCV13, PCV20, and PPV23, and to track how that proportion changed year over year using cluster-robust generalized linear models.¹

Serotype 3 Drives the Resurgence

Among the 1504 patients with SSUAD testing, 131 (8.78%) tested positive for a pneumococcal serotype. Serotype 3 was by far the most prevalent, detected in 52 cases, followed by serotype 8 in 17 cases, serotype 22F in 8 cases, and serotype 6A in 7 cases. Overall, vaccine-type pneumococcal pneumonia accounted for 5.41% (95% CI, 4.12%-7.06%) of all-cause CAP for PCV13 serotypes, 8.11% (95% CI, 6.35%-10.31%) for PCV20 serotypes, and 8.31% (95% CI, 6.27%-10.93%) for PPV23 serotypes.¹

The annual trend data were the most striking element of the report. Detection of S pneumoniae by the BINAX NOW urine antigen test increased significantly across the study period (OR, 1.77; 95% CI, 1.37-2.17), as did detection of PCV13 serotypes (OR, 1.53; 95% CI, 0.97-2.09) and serotype 3 specifically (OR, 1.85; 95% CI, 1.19-2.51). Among the subgroup of patients 60 years and older, increasing annual trends were observed for serotype 3 (OR, 1.84; 95% CI, 1.01-2.67), PCV13 serotypes (OR, 1.89; 95% CI, 0.89-2.89), PCV20 serotypes (OR, 1.57; 95% CI, 0.99-2.14), and PPV23 serotypes (OR, 1.47; 95% CI, 1.04-1.91).¹

The authors noted this resurgence, observed during the ongoing SARS-CoV-2 pandemic, has been primarily driven by an increase in serotype 3 cases—from 1.08% of all-cause CAP in 2020 to 6.16% in 2023. They suggested the reemergence of vaccine serotypes may reflect waning immunity or incomplete vaccine effectiveness.¹

Further, they noted that a global review of pneumococcal disease distribution found serotype 3 persists in both high-income and nonhigh-income countries, though the prevalence of specific serotypes varies by region: serotype 8 is more common in Europe and Asia, and serotype 4 is more prevalent in the United States and Canada.¹

Vaccine Coverage and a Persistent Gap in Uptake

By 2023, PCV20 serotype coverage of all-cause CAP reached nearly prepandemic levels, at 11.83% among adults 60 years and older and 11.22% among younger patients with comorbidities. The study authors highlighted 2 additional findings: an increase in serotype 3, PCV13, PCV20, and PPV23 serotypes among all-cause CAP cases in older adults between 2020 and 2023; and a persistently small coverage gap between PCV20 and PPV23.¹

Within the study cohort itself, only 20.68% of patients had received a pneumococcal vaccination, compared with 41.29% who had received an influenza vaccine. National German surveillance data cited in the study showed pneumococcal vaccination rates of just 11.3% to 13.2% among adults aged 60 to 64 years and 38.9% to 40.2% among those aged 70 to 74 years during the study period. PPV23 remained the standard adult vaccine in Germany until 2023 and likely accounted for the majority of those vaccinations.¹

The SSUAD assay used in the study did not cover 8 additional serotypes included in the newer 21-valent PCV Capvaxive (V116). The authors pointed to a separate multicenter German study of 514 adult patients with CAP, conducted between August 2022 and September 2024, which found that 13.5% of hospitalized adults 60 years and older had at least 1 detected serotype covered by V116, compared with 12.6% for PCV20 serotypes.¹

What This Means for Pharmacists

The persistence of vaccine-preventable serotypes alongside low vaccination uptake underscores an ongoing opportunity for pharmacists in both immunization and antimicrobial stewardship roles. A separate US study of pharmacist-led stewardship recommendations for hospitalized patients with CAP found that infectious diseases–trained pharmacists achieved a 72% overall acceptance rate for recommendations spanning antibiotic de-escalation, duration of therapy, and intravenous-to-oral conversion, with clinicians most receptive to intravenous-to-oral transition recommendations (80% acceptance) and least receptive to limiting duration of therapy (65% acceptance).²

Notably, 78% of the CAP patients evaluated in that study had already received a pneumococcal vaccine, reflecting the vaccine's now-common presence in hospitalized populations even as serotype coverage gaps persist.²

Current guidance recommends that adults 50 years and older, along with younger adults considered at risk for pneumococcal disease, receive either PCV20 alone or PCV15, followed a year later by PPV23. For patients previously vaccinated with older formulations, options differ: those who received only PCV13 can follow with PPV23 a year later, and those who received only PPV23 can receive PCV20 alone or PCV15 followed by another PPV23 dose a year later, with the interval shortened to 8 weeks for immunocompromised patients.³

The expanding menu of pneumococcal vaccines reflects the same serotype dynamics documented in the CAPNETZ cohort. Paul Licciardi, PhD, group leader of vaccine immunology at the Murdoch Children's Research Institute, told Drug Topics that the availability of PCV15, PCV20, and PCV21 stems directly from the bacteria's tendency to shift under vaccine pressure.⁵

"The bacteria have ways of evolving under vaccine pressure. You have these emergence of different types. That's why we've seen the 15-valent, 20-valent, and now the 21-valent," Licciardi said. He added that if a pharmacist has a choice among available formulations, the higher-valency vaccine is generally preferred, since PCV15 requires a follow-up PPV23 dose while the broader conjugate vaccines do not.⁵

Serotype composition also carries population-specific implications. Gretchen K. Garofoli, PharmD, BCACP, CTTS, FAPhA, clinical professor at the West Virginia University School of Pharmacy, noted that serotype 4—covered by PCV20 but not by the newer 21-valent formulation—remains more prevalent in the Western United States and among unhoused populations, a factor pharmacists should weigh alongside individual patient risk when selecting a product.⁴

Separate national surveillance data cited in that same report found that serotypes 3 and 8, the most frequently detected serotypes overall, remained broadly susceptible to tested antibiotics, while several other vaccine-covered serotypes were more strongly associated with antibiotic nonsusceptibility.⁴

Taken together, the CAPNETZ findings reinforce that pharmacists remain well positioned to close persistent adult pneumococcal vaccination gaps, particularly among patients 60 years and older who continue to bear the burden of vaccine-preventable serotype 3 disease.¹

REFERENCES

1. Bahrs C, Rose N, Barten-Neiner G, et al. Pneumococcal pneumonia in adults - re-emergence of vaccine serotypes: a prospective multicenter cohort study in Germany, 2020-2023. Pneumonia (Nathan). 2026;18(1):16. Published 2026 Jul 25. doi:10.1186/s41479-026-00204-3

2. Walker RE, Schulte R, Pallotta AM, et al. Acceptance of pharmacist-led stewardship recommendations for patients with community-acquired pneumonia. Antimicrob Steward Healthc Epidemiol. 2024;4(1):e181. Published 2024 Oct 17. doi:10.1017/ash.2024.399

3. Regunath H, Oba Y. Community-Acquired Pneumonia. StatPearls [Internet]. Updated January 26, 2024. Accessed July 27, 2026. https://www.ncbi.nlm.nih.gov/books/NBK430749/

4. Gallagher A. Antibiotic Resistance in Pneumococcal Disease Falls as Vaccine Serotypes Recede. Drug Topics. July 9, 2026. Accessed July 27, 2026. https://www.drugtopics.com/view/antibiotic-resistance-in-pneumococcal-disease-falls-as-vaccine-serotypes-recede

5. Nowosielski B, Licciardi P. Q&A: Pharmacists Help Patients Navigate Pneumococcal Vaccine Options. Drug Topics. July 20, 2026. Accessed July 27, 2026. https://www.drugtopics.com/view/pharmacists-help-patients-navigate-pneumococcal-vaccine-options