title: Combined schedules of pneumococcal conjugate and polysaccharide vaccines: is hyporesponsiveness an issue?
abstract: Streptococcus pneumoniae is a major cause of morbidity and mortality in children less than 5 years of age. Prevention of pneumococcal disease and death in children in the developing world through vaccination with recently developed, highly efficacious pneumococcal conjugate vaccines (PCVs) is now possible. Schedules combining PCV with 23-valent pneumococcal polysaccharide vaccine (PPV23) have been studied and proposed as a means to expand disease protection against serotypes not included in the PCVs. Studies of group A and C meningococcal polysaccharide vaccine and repeated doses of PPV23 in adults and children have shown that a state of immune tolerance, or hyporesponsiveness, can develop to repeated polysaccharide vaccine antigen exposures. In this Review, we describe the evidence for and against this hyporesponsiveness and explore the possible mechanisms for such an occurrence.
authors: Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA. klobrien@jhsph.edu
authors: Katherine L
authors: KL
authors: O'Brien
authors: Michael
authors: M
authors: Hochman
authors: David
authors: D
authors: Goldblatt
mesh_terms: D001428:Bacterial Vaccines; D004334:Drug Administration Schedule; D006801:Humans; D011008:Pneumococcal Infections / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology* / Q000627:therapeutic use
chemical_list: D001428:Bacterial Vaccines; D011135:Polysaccharides, Bacterial; C027158:polysaccharide C-substance (Streptococcus)