After being informed about the study and potential risks, patients will be screened to determine eligibility for the study and consented. Patients who meet eligibility requirements will be immunized with PCV 20. HIV-infected adults will be tested prior to and after vaccination by blood, nasal filter paper, and stool samples to characterize mucosal and systemic antibody responses . HIV-uninfected control adults will be tested at vaccination and post vaccination to characterize mucosal and systemic antibody responses .
