This literature study report has been received from the authors of a published literature article. The main aim of this cohort study was to assess vaccine response in a population of patients with Sickle Cell Disease (SCD). Institutional review board (IRB) approved cross sectional study. Study was performed at a Sickle Cell Center from July 2012 to July 2013. To be included, patients had to have a confirmed diagnosis of SCD (all genotypes) and had to have been seen in the SCD clinic during the target 12-month period. In addition, all patients had to have undergone vaccination response testing during this time period. Patients who had undergone stem cell transplant or had received (nonautologous) immunoglobulin and without a known immunization history were excluded. At study center, PNEUMOVAX 23 was administered at ages 2 and 5 and was then re-administered every 5 years as a preventative measure given the high burden of Invasive Pneumococcal Disease (IPD) in the SCD population. At the time this study was conducted, older patients who did not receive either of the PCV vaccines as children did not receive a dose of either PREVNAR (PCV-7 or PCV-13) when the vaccines were subsequently licensed. Immunoglobulin IgG titers were measured by laboratories using quantitative multiplex bead assay. Patients were classified as good responders if their serum levels of IgG were > 1.3mcg/mL to at least 50% of the 23 pneumococcal serotypes tested (i.e, > 12 serotypes with levels of > 1.3 mcg/mL) and Poor vaccine responders were defined as those who responded to = <11 of the designated serotypes. Data were originally collected on a total of 66 patients with SCD. The majority (n = 45) of patients had Hemoglobin SS (HbSS) disease. There were 37 male and 29 female patients. The average age of this cohort of patients was 10.9 years, with a range of 1 to 22 years. In study cohort of 66 patients, 64% (42/66) had received both the PCV-7 series and the PPV-23. However, 33% of the cohort (older patients) had only received PPV-23 as the PCV-7 series of vaccines was not available until the year 2000. This study was conducted before the initiation of PVC-13. Within the cohort of 66 patients who had received the PPV-23 vaccine, only 36% (24/66) were classified as good responders (adequate protection to at least 50% of the 23 serotypes). The remaining 64% of patients (42/66) demonstrated a poor vaccination response. Within the poor responding group, a large percentage of the patients, 64% (27/42), responded to < 25% of all serotypes. In this group of patients with the worst response, the majority (81.5%) had received their last PPV-23 over 36 months before antibody testing (P < 0.0001). There was no statistical difference in the average age of patients with poor versus good vaccination response. Those who demonstrated good response to PPV-23 were slightly younger, with an average age of 10.4 years (plus/minus 5.7) versus 13.0 years (plus/minus 5.4) for those patients with poor response. There was no difference in immunization response between patients who received the conjugate vaccine series (PCV-7) and the polysaccharide vaccine (PPV-23) and those who only received PPV-23. In addition, there were no differences in vaccination response seen in patients who had received only 1 PPV-23 or those who had received multiple PPV-23 vaccines. This report corresponds to 42 patients of unknown age and gender. The patients medical history was not reported. Concurrent conditions of patients included sickle cell disease. On an unknown date, the patients were vaccinated with PNEUMOVAX 23 dosage regimen route unknown. Other suspect therapies included PREVNAR. Concomitant medications were not reported. On an unknown date 42 patients who received vaccination demonstrated a poor vaccination response. The outcome of event was unknown. The reporter considered event to be related to suspect therapy PNEUMOVAX 23. Additional information has been requested.