Burden and characteristics of influenza A and B in Danish intensive care units during the 2009/10 and 2010/11 influenza seasons.
Influenza surveillance in Danish intensive care units (ICUs) was performed during the 2009/10 and 2010/11 influenza seasons to monitor the burden on ICUs. All 44 Danish ICUs reported aggregate data for incidence and point prevalence, and case-based demographical and clinical parameters. Additional data on microbiological testing, vaccination and death were obtained from national registers. Ninety-six patients with influenza A(H1N1)pdm09 were recorded in 2009/10; 106 with influenza A and 42 with influenza B in 2010/11. The mean age of influenza A patients was higher in 2010/11 than in 2009/10, 53 vs. 44 years (P = 0·004). No differences in other demographic and clinical parameters were detected between influenza A and B patients. In conclusion, the number of patients with severe influenza was higher in Denmark during the 2010/11 than the 2009/10 season with a shift towards older age groups in influenza A patients. Influenza B caused severe illness and needs consideration in clinical and public health policy.
European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Artillerivej 5, Stockholm, Sweden. gub@ssi.dk
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Gubbels
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TG
Krause
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Bragstad
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A
Perner
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Mølbak
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Glismann
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D017281:Cost of Illness; D003718:Denmark / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D009980:Influenza A virus; D009981:Influenza B virus; D007251:Influenza, Human / Q000453:epidemiology*; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008875:Middle Aged; D015995:Prevalence