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About one-third of pneumococcal serotypes in a large study of community-acquired pneumonia are not included in some current pneumococcal conjugate vaccines.

New pneumococcal vaccines with expanded serotype coverage are needed to augment efforts to prevent the considerable burden associated with community-acquired pneumonia (CAP), as two of three current vaccines do not protect against about one-third of the detected serotypes, according to findings from a prospective surveillance study published in Clinical Infectious Diseases.

“Understanding the pneumococcal serotypes causing CAP is essential for evaluating the impact of pneumococcal vaccines,” Wesley H. Self, MD, and colleagues wrote.

The study cohort comprised adults hospitalized with CAP at three hospitals from September 1, 2018, to October 31, 2022. Researchers evaluated the pneumococcal etiology using cultures, a urinary antigen detection test, and serotype-specific urinary antigen detection assays that identify 30 pneumococcal serotypes found in the investigational pneumococcal conjugate vaccine V116 and licensed vaccines PCV15 and PCV20 (except serotype 15B). The researchers utilized serotype-specific urinary antigen detection results to measure the distribution of pneumococcal serotypes.

Common Serotypes Include 3, 22F, 19A, 35B, 9N

The analysis included 2,917 adults hospitalized with CAP (median age, 60; 67.5% White). Among these patients, 352 (12.1%) had Streptococcus pneumoniae, including 51 (1.7%) with invasive pneumococcal pneumonia.

The most common serotypes recorded were 3, 22F, 19A, 35B, 9N, 19F, 23A, and 11A. Serotypes in V116 were identified in 272 patients (9.3%), compared with 196 (6.7%) in PCV20 (P<0.001) and 168 (5.8%) in PCV15 (P<0.001). Additionally, 120 (4.1%) had serotypes in V116 but not in PCV15 or PCV20, representing 38.0% of detections.

“Patients with pneumococcal CAP experienced significant morbidity and mortality, with approximately one-quarter treated in an [ICU] and 6% dying before hospital discharge,” Dr. Self and colleagues wrote. “These results highlight that S. pneumoniae continues to be an important cause of severe pneumonia among adults in the US more than 20 years after introduction of pneumococcal conjugate vaccines and after COVID-19 altered the epidemiology of respiratory infections.”

Expanding Serotype Coverage in New Vaccines

Dr. Self and colleagues also noted that the development of new pneumococcal vaccines with more extensive serotype coverage has the potential to avert the considerable burdens associated with CAP in adults.

“Importantly, approximately one-third of pneumococcal serotypes identified in this study are not included in the [two] pneumococcal conjugate vaccines currently in use, suggesting that expansion of serotypes covered by future pneumococcal vaccines could potentially prevent a substantial burden of severe pneumococcal disease,” the researchers wrote.

*Since Dr. Self and colleagues’ study was published, the FDA approved the 21-valent pneumococcal conjugate vaccine V116 in an effort to expand vaccine coverage to more serotypes.