Age-related immune response to pneumococcal polysaccharide vaccination: lessons for the clinic

Due to distinct immunological limitations, both infants and elderly individuals are highly susceptible to Streptococcus pneumoniae. Routine immunization of children with the conjugate vaccine over the past decade has substantially reduced incidence of vaccine-serotype related invasive pneumococcal disease in both vaccinated and unvaccinated persons of all ages. However, disease burden remains high in the elderly despite the effects of herd protection and recommended use of polysaccharide vaccine in this population for over 30 years. An increase in drug resistance and incidence of infections caused by non-vaccine serotypes emphasize the need to improve current vaccination strategies. Recent efforts to identify age-associated defects in vaccine response and the use of conjugate vaccine and potential alternatives in adults are discussed.