title: Trends in serotype prevalence in invasive pneumococcal disease before and after infant pneumococcal vaccination in Belgium, 2002-2010.
abstract: OBJECTIVE
  We evaluated the effect of the infant 7-valent pneumococcal conjugate vaccine (PCV7) program on the serotype distribution in invasive pneumococcal disease in the Belgian population.
  
  
  METHODS
  Serotyping was performed on 13,998 bacteraemic and pleural fluid isolates sent to the National Reference Laboratory between 2002 and 2010. We compared the distribution of serogroups (SGs) between the pre- (2002-2004) and post-PCV7 (2007-2010) era for children (<18 years), adults (18-59 years) and older individuals (≥60 years).
  
  
  RESULTS
  The proportion of cases caused by PCV7-SGs in subjects <18 years decreased from 69% pre-PCV7 to 26% post-PCV7 (p<0.005) and the majority of cases caused by PCV7-SGs were caused by SG 19. Post-PCV7, the prevalence of PCV7-SGs decreased from 38% to 29% and from 57% to 35% in subjects in the age groups 18-59 and ≥60 years, respectively (p<0.005). Post-PCV7 the prevalence of SGs 1, 7 and 19 increased significantly in subjects aged <18 years. The increase of SG19 was caused by an increase of serotype 19A in this age group (p<0.005). After the introduction of infant PCV7 the largest rise in prevalence occurred for SGs 7, 12 and 22 (p<0.005) in the two older age categories. Post PCV7, the overall PCV13 and 23-valent pneumococcal polysaccharide vaccine coverage rates decreased from 85% to 69% and from 96% to 93%, respectively (p<0.005).
  
  
  CONCLUSIONS
  PCV7 has an impact on SG distribution of invasive pneumococcal disease isolates of vaccinated and unvaccinated subjects. SG replacement forms a major threat to the success of PCV7. PCV13, including several additional replacement serotypes (STs 1, 7F, 19A), represents an attractive alternative.
authors.affiliation: Department of Internal Medicine, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Laurens
authors.initials: L
authors.lastname: Liesenborghs
authors.forename: Jan
authors.initials: J
authors.lastname: Verhaegen
authors.forename: Willy E
authors.initials: WE
authors.lastname: Peetermans
authors.forename: Jozef
authors.initials: J
authors.lastname: Vandeven
authors.forename: Johan
authors.initials: J
authors.lastname: Flamaing
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001530:Belgium / Q000453:epidemiology; D001769:Blood / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000382:microbiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000302:isolation & purification*; D055815:Young Adult
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines