Evaluation of PCV21 Vaccination Among PPSV23-experienced, Immunocompromised Elderly Veterans

Inclusion Criteria: * Subject meets the CDC definition of an immunocompromising condition o chronic renal failure, congenital or acquired asplenia, generalized malignancy, HIV infection, Hodgkin disease, iatrogenic immunosuppression, leukemia, lymphoma, multiple myeloma, nephrotic syndrome, sickle cell disease or other hemoglobinopathies, and solid organ transplant. * Have received at least 1 dose of PPSV23 Exclusion Criteria: * Less than 5 years since last receipt of PPSV23 validated to patient medical record and Immunize Nevada Website * Previous administration of PCV20 * Previous administration of PCV13 * Previous administration of PCV15 * Less than 14 days since administration of any COVID19 vaccination * Previous history of Invasive Pneumococcal Disease (IPD) * Antibiotic treatment within the previous 90 days