This study will assess the safety, tolerability and immune response of 13-valent pneumococcal conjugate vaccine (13vPnC) compared with 23-valent Pneumococcal Polysaccharide Vaccine (23vPS). Although the study started with only 1 population, amendments to the original protocol will now reflect three participant populations. Three age cohorts will be enrolled. The first cohort (age 60-64) will be blinded. Cohort 2 (age 50-59) and cohort 3 (age 18-49) are open label. Subjects in cohorts 1 and 2 will receive 2 vaccinations 3-4 years apart. Subjects in cohort 3 will receive 1 vaccination. All participants should be naĂŻve of 23vPS. Comparisons of immune responses from the different cohorts will be done.
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Serotype-specific Opsonophagocytic Activity (OPA) Geometric Mean Titers (GMTs) 1 Month After Vaccination 1
Timeframe: One month after vaccination 1
Percentage of Participants Achieving At Least a 4-fold Rise in OPA Titer for Serotype 6A 1 Month After Vaccination 1 in Cohort 1
Timeframe: One month after vaccination 1
Serotype-specific Opsonophagocytic Activity (OPA) Geometric Mean Titers (GMTs) 1 Month After Vaccination for 12 Common Serotypes in 13vPnC/23vPS Group Relative to 23vPS Group and 23vPS/23vPS Group
Timeframe: One month after vaccination 1 and One month after vaccination 2/Year 3 to 4