title: Serotype-specific effect of influenza on adult invasive pneumococcal pneumonia.
abstract: BACKGROUND
  Influenza affects host susceptibility to pneumococcus. We sought to evaluate whether this relationship varies by pneumococcal serotype using a large epidemiological database covering 3 decades.
  
  
  METHODS
  Weekly rates of invasive pneumococcal pneumonia (IPP) were obtained from the Danish National Laboratory Surveillance System, and influenza-like illness (ILI) data were collected from Danish sentinel surveillance, Statens Serum Institut, 1977-2007. We fit Poisson regression models for each age and comorbidity group, with predictors for seasonality and secular changes, ILI activity, and serotype.
  
  
  RESULTS
  Among individuals with low levels of comorbidities, influenza had the largest impact on IPP incidence among low-invasiveness serotypes (influenza attributable percent: 17.9%, 95% confidence interval [CI], 13.6-21.9) as compared with high-invasiveness serotypes (6.7%, 95% CI, 3.8%-11.7%). Among those with higher levels of comorbidities, the effect of influenza was smaller, but high-invasiveness serotypes increased more than low-invasiveness serotypes (8.9% [95% CI, 6.6-11.8] vs. 1.3% [95% CI, -1.6-5.4].
  
  
  CONCLUSIONS
  Influenza was associated with the greatest increases in the incidence of disease caused by serotypes with lower invasive potential and among individuals with low levels of comorbid conditions. The importance of influenza for adult IPP varies by serotype and host comorbidity.
authors.affiliation: Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, Maryland.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Weinberger
authors.forename: Zitta B
authors.initials: ZB
authors.lastname: Harboe
authors.forename: Cécile
authors.initials: C
authors.lastname: Viboud
authors.forename: Tyra G
authors.initials: TG
authors.lastname: Krause
authors.forename: Mark
authors.initials: M
authors.lastname: Miller
authors.forename: Kåre
authors.initials: K
authors.lastname: Mølbak
authors.forename: Helle B
authors.initials: HB
authors.lastname: Konradsen
mesh_terms: D000328:Adult; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology / Q000821:virology; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology* / Q000382:microbiology; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology* / Q000821:virology; D016012:Poisson Distribution; D012703:Serotyping
keywords: coinfection; comorbidity; influenza; interaction; pneumococcus; regression
references.citation: Infect Control Hosp Epidemiol. 2000 Nov;21(11):711-7
references.pmid: 11089655
references.citation: Lancet Infect Dis. 2004 Mar;4(3):144-54
references.pmid: 14998500
references.citation: Public Health Rep. 1963 Jun;78(6):494-506
references.pmid: 19316455
references.citation: Lancet Infect Dis. 2005 Feb;5(2):83-93
references.pmid: 15680778
references.citation: Clin Infect Dis. 2010 Feb 1;50(3):329-37
references.pmid: 20047478
references.citation: J Infect Dis. 2004 Oct 1;190(7):1203-11
references.pmid: 15346329
references.citation: BMC Infect Dis. 2006 Mar 20;6:58
references.pmid: 16549029
references.citation: BMC Infect Dis. 2011 Dec 16;11:350
references.pmid: 22176601
references.citation: Future Microbiol. 2012 May;7(5):609-24
references.pmid: 22568716
references.citation: Lancet. 2001 Oct 27;358(9291):1410-6
references.pmid: 11705487
references.citation: Clin Infect Dis. 2000 May;30(5):784-9
references.pmid: 10816149
references.citation: Arch Intern Med. 1974 Sep;134(3):505-10
references.pmid: 4152800
references.citation: J Infect Dis. 2012 Feb 1;205(3):458-65
references.pmid: 22158564
references.citation: PLoS Med. 2011 Jun;8(6):e1001042
references.pmid: 21687693
references.citation: J Infect Dis. 2010 Oct 15;202(8):1287-95
references.pmid: 20822454
references.citation: J Infect Dis. 2004 Mar 1;189(5):785-96
references.pmid: 14976594
references.citation: Science. 2006 Apr 21;312(5772):447-51
references.pmid: 16574822
references.citation: PLoS One. 2011 Apr 27;6(4):e18687
references.pmid: 21556151
references.citation: J Infect Dis. 2006 Sep 1;194(5):682-8
references.pmid: 16897668
references.citation: Pediatr Infect Dis J. 2000 Dec;19(12):1141-7
references.pmid: 11144373
references.citation: Clin Infect Dis. 2010 Jan 15;50(2):175-83
references.pmid: 20014948
references.citation: Infect Immun. 2008 Feb;76(2):646-57
references.pmid: 18039836
references.citation: Clin Infect Dis. 2006 Feb 15;42(4):451-9
references.pmid: 16421787
references.citation: Vaccine. 2009 Aug 21;27 Suppl 3:C9-C14
references.pmid: 19683658
references.citation: Vaccine. 2008 Jul 4;26(29-30):3765-71
references.pmid: 18513840
references.citation: J Infect Dis. 2005 Sep 1;192(5):791-800
references.pmid: 16088828
references.citation: Clin Infect Dis. 2010 Sep 15;51(6):692-9
references.pmid: 20715907
references.citation: Proc Natl Acad Sci U S A. 2011 Sep 27;108(39):16416-21
references.pmid: 21930918
references.citation: Pediatr Infect Dis J. 2012 Jun;31(6):650-3
references.pmid: 22333697
references.citation: Pediatr Infect Dis J. 2010 Jun;29(6):519-23
references.pmid: 20051928
references.citation: Euro Surveill. 2006;11(10):254-6
references.pmid: 17130655
references.citation: Am J Hyg. 1946 Sep;44(2):231-6
references.pmid: 21003018
references.citation: Epidemiology. 2011 Mar;22(2):199-207
references.pmid: 21646962
references.citation: FASEB J. 2010 Jun;24(6):1789-98
references.pmid: 20097876
references.citation: Clin Microbiol Rev. 2006 Jul;19(3):571-82
references.pmid: 16847087
references.citation: PLoS Pathog. 2009 Jun;5(6):e1000476
references.pmid: 19521509
references.citation: Med J Aust. 2011 Feb 21;194(4):207
references.pmid: 21401468
references.citation: PLoS Med. 2009 May 26;6(5):e1000081
references.pmid: 19468297
references.citation: J Infect Dis. 2008 Oct 1;198(7):962-70
references.pmid: 18710327
references.citation: Am J Med. 2005 Mar;118(3):285-91
references.pmid: 15745727