title: Randomised revaccination with pneumococcal polysaccharide or conjugate vaccine in asplenic children previously vaccinated with polysaccharide vaccine.
abstract: OBJECTIVE
  Asplenic children are at high risk of invasive pneumococcal infection. In this group, the American Academy of Pediatrics recommends a single revaccination with the 23-valent polysaccharide vaccine (PSV23) 3-5 years after a previous PSV23 dose. Despite potential advantages, there are few data available regarding the safety and immunogenicity of the heptavalent pneumococcal conjugate vaccine (PCV7) in this population. The aim of the study was to prospectively determine and to compare, in asplenic children, the vaccine specific antibody titres against the seven serotypes included in the PCV7 after administration of one dose of PCV7 or of PSV23, 3 years or more after an initial vaccination with PSV23.
  
  
  METHODS
  In this randomised, single-centre study, antibody titres were monitored at baseline, at 1 and 6 months after revaccination in 21 children with anatomic or functional asplenia. Response was considered as positive when there was a four-fold increase in antibody titres from baseline.
  
  
  RESULTS
  The most frequently reported adverse events were local reactions in 7/11 of PCV7 subjects and in 5/8 of PSV23 subjects, and general reactions (loss of appetite, sleepiness) in 5/11 of PCV7 subjects and in 1/8 of PSV23 subjects; without any serious adverse events. One child in the PCV7 group had increased temperature (38.4 degrees C). At least half of the PCV7 children responded to four or five serotypes, while more than half of the PSV23 subjects responded to less than 3 serotypes (p=0.285). After 1 month, the immune response for serotype 23F was significantly greater after PCV7 vaccination than after PSV23 vaccination (p=0.036).
  
  
  CONCLUSIONS
  PCV7 revaccination is safe and immunogenic in asplenic children previously vaccinated with PSV23, and could provide appropriate booster response in this high-risk population. The clinical repercussion on invasive pneumococcal diseases remains to be demonstrated.
authors.affiliation: Paediatric Clinical Investigation Centre, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium. francoise.smets@pedi.ucl.ac.be
authors.forename: F
authors.initials: F
authors.lastname: Smets
authors.forename: A
authors.initials: A
authors.lastname: Bourgois
authors.forename: C
authors.initials: C
authors.lastname: Vermylen
authors.forename: B
authors.initials: B
authors.lastname: Brichard
authors.forename: P
authors.initials: P
authors.lastname: Slacmuylders
authors.forename: S
authors.initials: S
authors.lastname: Leyman
authors.forename: E
authors.initials: E
authors.lastname: Sokal
mesh_terms: D000293:Adolescent; D000907:Antibodies, Bacterial / Q000097:blood; D002648:Child; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007117:Immunization, Secondary / Q000009:adverse effects*; D008297:Male; D022401:Meningococcal Vaccines / Q000009:adverse effects* / Q000276:immunology*; D022242:Pneumococcal Vaccines / Q000009:adverse effects* / Q000276:immunology*; D011446:Prospective Studies; D013154:Spleen / Q000276:immunology*; D013156:Splenectomy; D013997:Time Factors
chemical_list: C414006:23-valent pneumococcal capsular polysaccharide vaccine; D000907:Antibodies, Bacterial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines