Challenge
Streptococcus pneumoniae is associated with significant morbidity and mortality in older adults. Vaccination with 23-valent Pneumococcal polysaccharide vaccine (PPV23) and pneumococcal conjugate vaccines (PCV) can prevent disease and is recommended for adults over 60 years of age in most high income countries, but WHO does not currently have recommendations for pneumococcal vaccines in those over 5 years of age. The optimal time for pneumococcal immunization of older adults needs to strike a balance between initial vaccine responses and duration of protection but the degree that pneumococcal vaccine immunogenicity declines with age is unknown.
Approach
We conducted a systematic literature review to assess the association between age at pneumococcal vaccination and immunogenicity in adults over 50 years of age. We explored the optimal age to vaccinate older, relatively healthy adults against pneumococcal disease by analyzing data on the immunogenicity of pneumococcal vaccines 1-month after immunization and also the impact of age at vaccination on the persistence of antibody responses. Both serotype-specific IgG and functional antibody measured using opsonophagocytic killing assays were assessed.
Results
Age-related differences in antibody responses to pneumococcal vaccines were generally small, predominantly in the very elderly, and unlikely to be biologically relevant. Decisions about the timing of pneumococcal vaccines in adults should be based on disease burden profile and consequent risk of infection.
