University of Oulu

Ylipalosaari, P., Ala-Kokko, T. I., Laurila, J., Ahvenjärvi, L., & Syrjälä, H. (2017). ICU-treated influenza A(H1N1) pdm09 infections more severe post pandemic than during 2009 pandemic: a retrospective analysis. BMC Infectious Diseases, 17(1).

ICU-treated influenza A(H1N1) pdm09 infections more severe post pandemic than during 2009 pandemic : a retrospective analysis

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Author: Ylipalosaari, Pekka1; Ala-Kokko, Tero I.2,3; Laurila, Jouko2,3;
Organizations: 1Department of Infection Control, Oulu University Hospital, Box 21, FIN-90029, Oulu, OYS, Finland
2Department of Anesthesiology, Division of Intensive Care, Oulu University Hospital, FIN-90029, Oulu, OYS, Finland
3Medical Research Center, Research Group of Surgery, Anesthesiology and Intensive Care, University of Oulu, Oulu, Finland
4Department of Radiology, Oulu University Hospital, FIN-90029, Oulu, OYS, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.5 MB)
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Language: English
Published: Springer Nature, 2017
Publish Date: 2019-09-17


Background: We compared in a single mixed intensive care unit (ICU) patients with influenza A(H1N1) pdm09 between pandemic and postpandemic periods.

Methods: Retrospective analysis of prospectively collected data in 2009–2016. Data are expressed as median (25th–75th percentile) or number (percentile).

Results: Seventy-six influenza A(H1N1) pdm09 patients were admitted to the ICU: 16 during the pandemic period and 60 during the postpandemic period. Postpandemic patients were significantly older (60 years vs. 43 years, p < 0.001) and less likely to have epilepsy or other neurological diseases compared with pandemic patients (5 [8.3%] vs. 6 [38%], respectively; p = 0.009). Postpandemic patients were more likely than pandemic patients to have cardiovascular disease (24 [40%] vs. 1 [6%], respectively; p = 0.015), and they had higher scores on APACHE II (17 [13–22] vs. 14 [10–17], p = 0.002) and SAPS II (40 [31–51] vs. 31 [25–35], p = 0.002) upon admission to the ICU. Postpandemic patients had higher maximal SOFA score (9 [5–12] vs. 5 [4–9], respectively; p = 0.03) during their ICU stay. Postpandemic patients had more often septic shock (40 [66.7%] vs. 8 [50.0%], p = 0.042), and longer median hospital stays (15.0 vs. 8.0 days, respectively; p = 0.006). During 2015–2016, only 18% of the ICU- treated patients had received seasonal influenza vaccination.

Conclusions: Postpandemic ICU-treated A(H1N1) pdm09 influenza patients were older and developed more often septic shock and had longer hospital stays than influenza patients during the 2009 pandemic.

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Series: BMC infectious diseases
ISSN: 1471-2334
ISSN-E: 1471-2334
ISSN-L: 1471-2334
Volume: 17
Article number: 728
DOI: 10.1186/s12879-017-2829-3
Type of Publication: A1 Journal article – refereed
Field of Science: 3111 Biomedicine
Copyright information: © The Authors 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.