How effective is the PPSV23 for the prevention of serotype-specific community-acquired pneumonia (CAP)? Thanks to new technology, a study has come up with the answer to that question.

The study, published in the journal Microorganisms, sought to assess the effectiveness of PPSV23 for the prevention of CAP hospitalizations due to vaccine-contained serotypes. The analysis was a nested case-control, test-negative study design of adult patients hospitalized for CAP between June 1, 2014, and March 31, 2017.

University of Louisville–led researchers pointed out that cases included patients with CAP due to a Streptococcus pneumoniae serotype contained in the PPSV23, and they performed urinary antigen detection of the 23 serotypes.

For the study, the focus was on PPSV23 vaccination alone and no other pneumococcal vaccination. With 3,686 patients included in the analysis, the PPSV23 vaccination was documented in 608 (16%) patients, and the PPSV23-serotype CAP was detected in 48 (8%) PPSV23-vaccinated patients and in 288 (9%) nonvaccinated patients.

The researchers reported that unadjusted vaccine effectiveness for preventing PPSV23-serotype CAP was 17% (95% CI: -13%-40%), while adjusted estimates for preventing PPSV23-serotype CAP was 14% (95% CI: -17%-38%).

"In this study, PPSV23 vaccination offered no protection against PPSV23-serotype CAP hospitalization in adults," the authors explained. "This is the first PPSV23 vaccine effectiveness study from the United States that utilized a urinary antigen detection assay as the main method for S pneumoniae serotyping. This study highlights the need for more effective vaccines in the prevention of hospitalization due to S pneumoniae CAP."

Background information in the articles noted that, in the U.S., PPSV23 was approved for use in 1983 for the prevention of pneumococcal disease caused by the 23 S pneumoniae serotypes.

Researchers advised that PPSV23 vaccination appears to be effective in preventing invasive pneumococcal disease in adults with estimated effectiveness of 60% to 70% reported by the CDC.

"However, there is no consensus regarding PPSV23 vaccination for the prevention of hospitalized CAP due to serotypes contained in the PPSV23," the authors wrote. "The primary challenge with this type of study has been the identification of vaccine-specific serotypes. New technologies using non-culture-based techniques such as the 13-valent Luminex multiplex urinary antigen detection (UAD) assay have demonstrated high sensitivity and specificity for serotypes covered by the 13-valent pneumococcal conjugated vaccine (PCV13) in adults hospitalized with CAP. More recently, increased serotype coverage available in the UAD-2 assay now facilitates the identification of 23 serotypes in hospitalized adult patients. With the UAD-2 assay, the estimation of PPSV23 vaccine effectiveness (VE) for the prevention of hospitalized vaccine-type infections is now possible."

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