AUTHOR=Janssen Lisanne M. A. , Heron Michiel , Murk Jean-Luc , Leenders Alexander C. A. P. , Rijkers Ger T. , de Vries Esther 

TITLE=Focusing on Good Responders to Pneumococcal Polysaccharide Vaccination in General Hospital Patients Suspected for Immunodeficiency. A Decision Tree Based on the 23-Valent Pneumococcal IgG Assay

JOURNAL=Frontiers in Immunology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.02496

DOI=10.3389/fimmu.2019.02496

ISSN=1664-3224

ABSTRACT=<p><bold>Background and Aim:</bold> Recently, the 23-valent IgG-assay was suggested as screening assay to identify <italic>poor</italic> responders to pneumococcal polysaccharide (PnPS)-vaccination with the serotype-specific assay as a second-line test. However, in a low pre-test probability general hospital setting predicting <italic>good</italic> responders could be more valuable to reduce the number of samples needing serotyping.</p><p><bold>Methods:</bold> Serotype-specific PnPS antibody-assays were performed for suspected immunodeficiency in two Dutch general hospitals (Jeroen Bosch Hospital, 's-Hertogenbosch; Elisabeth Tweesteden Hospital, Tilburg). 23-Valent PnPS antibody-assays were subsequently performed in archived material. Data were analyzed using receiver operating characteristic curves (AUC) and agreement indices (ICC).</p><p><bold>Results:</bold> Sera of 284 patients (348 samples) were included; 23-valent IgG-titres and the corresponding sum of PnPS-serotype specific antibodies showed moderate correlation (ICC = 0.63). In 232 conjugated-pneumococcal-vaccine-naïve patients (270 samples), a random 23-valent IgG-titer could discriminate between samples with and without ≥7/11, ≥7/13, or ≥6/9 pneumococcal serotypes when both cut-off values 0.35 and 1.0 μg/ml were used (AUC 0.86 and 0.92, respectively). All patients with a pre-immunization-titer ≥38.2 μg/ml and/or post-immunization-titer ≥96.1 μg/ml and none with a post-immunization-titer ≤38.5 μg/ml exhibited a good response to PnPS vaccination. Using these breakpoints as screening test to predict <italic>good</italic> responders, only 24% of patients would require further serotyping, as opposed to 68% if breakpoints to predict <italic>poor</italic> responders would have been used.</p><p><bold>Conclusion:</bold> In a low pre-test probability setting, the 23-valent IgG-assay proved to be a reliable screening test for good responders in conjugated-pneumococcal-vaccine-naïve patients, reducing the overall number of patient samples needing further serotyping, thus reducing overall costs of pneumococcal vaccination response assessment.</p>