title: Serotype epidemiology of invasive pneumococcal disease in Swiss adults: a nationwide population-based study.
abstract: BACKGROUND
  In Switzerland, the heptavalent (PCV7) and 13-valent pneumococcal conjugate vaccine (PCV13) were recommended for all infants aged <2 years in 2007 and 2011, respectively. Due to herd effects, a protective impact on the invasive pneumococcal disease (IPD) rates in adults had been expected.
  
  
  METHODS
  Within this study, data from the nationwide mandatory surveillance was analyzed for all adult patients ≥16 years with IPD of known serotype/serogroup during 2003-2012. Trend (for IPD cases from 2003 to 2012) and logistic regression analyses (2007-2010) were performed to identify changes in serotype distribution and to identify the association of serotypes with age, clinical manifestations, comorbidities and case fatality, respectively.
  
  
  RESULTS
  The proportion of PCV7 serotypes among all IPD cases (n=7678) significantly declined in adults from 44.7% (2003) before to 16.7% (2012) after the recommendation of PCV7 (P<0.001). In contrast, the proportion of non-PCV7 serogroup/serotypes increased for non-PCV13 but also PCV13 serotypes (not included in PCV7) at the same time. Serotype distribution varied significantly across ages, clinical manifestations and comorbidities. Serotype was furthermore associated with case fatality (P=0.001). In a multivariable logistic regression model, analyzing single serotypes showed that case-fatality was increased for the serotypes 3 (P=0.008), 19A (P=0.03) and 19F (P=0.005), compared to serotype 1 and 7F.
  
  
  CONCLUSIONS
  There was a significant decline in PCV7 serotypes among adults with IPD in Switzerland after introduction of childhood vaccination with PCV7. Pneumococcal serotypes were associated with case fatality, age, clinical manifestation and comorbidities of IPD in adults. These results may prove useful for future vaccine recommendations for adults in Switzerland.
authors: Department of Infectious Diseases, Inselspital, Bern University Hospital and University of Bern, Switzerland; Institute for Infectious Diseases, University of Bern, Switzerland.
authors: Jurka
authors: J
authors: Meichtry
authors: Federal Office of Public Health, Bern, Switzerland.
authors: Rita
authors: R
authors: Born
authors: Institute for Infectious Diseases, University of Bern, Switzerland.
authors: Marianne
authors: M
authors: Küffer
authors: Institute of Social and Preventive Medicine, University of Bern, Switzerland.
authors: Marcel
authors: M
authors: Zwahlen
authors: Department of Infectious Diseases and Hospital Hygiene, Cantonal Hospital of St. Gallen, Switzerland.
authors: Werner C
authors: WC
authors: Albrich
authors: Institute for Infectious Diseases, University of Bern, Switzerland.
authors: Silvio D
authors: SD
authors: Brugger
authors: Department of Infectious Diseases, Inselspital, Bern University Hospital and University of Bern, Switzerland; Institute for Infectious Diseases, University of Bern, Switzerland.
authors: Kathrin
authors: K
authors: Mühlemann
authors: Department of Infectious Diseases, Inselspital, Bern University Hospital and University of Bern, Switzerland; Institute for Infectious Diseases, University of Bern, Switzerland. Electronic address: Markus.Hilty@ifik.unibe.ch.
authors: Markus
authors: M
authors: Hilty
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D006801:Humans; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage; D018571:Sentinel Surveillance; D016036:Seroepidemiologic Studies; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification*; D013557:Switzerland / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D022242:Pneumococcal Vaccines
keywords: Case fatality; Epidemiology; Manifestations; Serotypes; Streptococcus pneumoniae; Switzerland