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Editor, Senior Moderator
Serotype-specific effect of influenza on adult invasive pneumococcal pneumonia
Daniel M. Weinberger*,1,
Zitta B. Harboe*,2,
C?cile Viboud1,
Tyra G. Krause3,
Mark Miller1,
K?re M?lbak3 and
Helle B. Konradsen2
+ Author Affiliations
1Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
2Neisseria and Streptococcus Reference Center, Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark
3Department of Epidemiology, Statens Serum Institut, Copenhagen, Denmark
Corresponding author: Zitta B. Harboe, Neisseria and Streptococcus Reference Center, Department of Microbiological Surveillance and Research, Statens Serum Institut, ?restads Boulevard 5, DK-2300 S Copenhagen, Denmark, Tel: +45-3268 3044, e-mail:zit@ssi.dk
↵* These authors contributed equally to the work.
Abstract
Background. Influenza affects host susceptibility to pneumococcus. However it is not clear whether this relationship varies by pneumococcal serotype. We sought to quantify the impact of influenza on the incidence of different serotypes using a large epidemiological database covering three 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%CI:13.6-21.9), as compared with high invasiveness serotypes (6.7%, 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% [6.6-11.8] vs 1.3% [-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 co-morbidity.
http://jid.oxfordjournals.org/content/early/2013/07/30/infdis.jit375.abstract
Daniel M. Weinberger*,1,
Zitta B. Harboe*,2,
C?cile Viboud1,
Tyra G. Krause3,
Mark Miller1,
K?re M?lbak3 and
Helle B. Konradsen2
+ Author Affiliations
1Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
2Neisseria and Streptococcus Reference Center, Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark
3Department of Epidemiology, Statens Serum Institut, Copenhagen, Denmark
Corresponding author: Zitta B. Harboe, Neisseria and Streptococcus Reference Center, Department of Microbiological Surveillance and Research, Statens Serum Institut, ?restads Boulevard 5, DK-2300 S Copenhagen, Denmark, Tel: +45-3268 3044, e-mail:zit@ssi.dk
↵* These authors contributed equally to the work.
Abstract
Background. Influenza affects host susceptibility to pneumococcus. However it is not clear whether this relationship varies by pneumococcal serotype. We sought to quantify the impact of influenza on the incidence of different serotypes using a large epidemiological database covering three 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%CI:13.6-21.9), as compared with high invasiveness serotypes (6.7%, 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% [6.6-11.8] vs 1.3% [-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 co-morbidity.
http://jid.oxfordjournals.org/content/early/2013/07/30/infdis.jit375.abstract