title: Estimating the burden of A(H1N1)pdm09 influenza in Finland during two seasons.
abstract: In Finland, the pandemic influenza virus A(H1N1)pdm09 was the dominant influenza strain during the pandemic season in 2009/2010 and presented alongside other influenza types during the 2010/2011 season. The true number of infected individuals is unknown, as surveillance missed a large portion of mild infections. We applied Bayesian evidence synthesis, combining available data from the national infectious disease registry with an ascertainment model and prior information on A(H1N1)pdm09 influenza and the surveillance system, to estimate the total incidence and hospitalization rate of A(H1N1)pdm09 infection. The estimated numbers of A(H1N1)pdm09 infections in Finland were 211 000 (4% of the population) in the 2009/2010 pandemic season and 53 000 (1% of the population) during the 2010/2011 season. Altogether, 1·1% of infected individuals were hospitalized. Only 1 infection per 25 was ascertained.
authors.affiliation: Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Shubin
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Virtanen
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Toikkanen
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: O
authors.initials: O
authors.lastname: Lyytikäinen
authors.affiliation: Department of Vaccination and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Auranen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001499:Bayes Theorem; D002648:Child; D002675:Child, Preschool; D005387:Finland / Q000453:epidemiology; D006760:Hospitalization; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D008875:Middle Aged; D015233:Models, Statistical; D058873:Pandemics / Q000706:statistics & numerical data*; D055815:Young Adult