The Immunogenicity of Prevnar 13 in Immunocompetent Older Adults with Stable High Risk Conditions is Comparable to that in Healthy Older Adults

Background:

Starting at about age 50, adults are at increased risk for developing pneumococcal infections. Predisposing factors for serious pneumococcal community-acquired pneumonia and invasive pneumococcal disease include common chronic medical conditions such as cardiovascular, pulmonary, liver, and renal diseases, as well as diabetes mellitus. Previous studies of the immunogenicity of PCV13 have shown that the vaccine elicits robust immune responses in populations of immunocompetent adults 50 years and over that included healthy adults as well as those with stable high risk conditions. In this evaluation, we compared the  functional immune responses of study participants with and without high risk conditions.

Methods:

We evaluated two studies that enrolled pneumococcal vaccine naïve adults 50-64 years of age as well as a study that enrolled adults ≥70 years of age who had previously received 23-valent pneumococcal polysaccharide vaccine. In these studies, serotype-specific functional antibody titers 1 month after vaccination with PCV13 were determined by opsonophagocytic activity (OPA) assays. OPA geometric mean titers (GMTs) of the high risk subjects were descriptively compared to those in the non-high risk subjects. 

Results:

The clinical studies were not stratified for risk conditions at enrolment, and numbers of subjects varied. Each high-risk group demonstrated a rise in serotype specific OPA antibody titer compared to pre-immunization titers. When examining responses after vaccination with PCV13 in pneumococcal vaccine-naïve and pre-immunized subjects, high-risk subjects exhibited similar OPA responses compared to non-high risk subjects.

Conclusion:

The patterns of functional anti-pneumococcal immune responses following PCV13 immunization in adults with high-risk conditions were comparable to those in subjects without high risk conditions, indicating that vaccinating immunocompetent high-risk adults with PCV13 likely results in analogous benefits to those experienced by non-high risk adults.