Pandemic vaccination strategies and influenza severe outcomes during the influenza A(H1N1)pdm09 pandemic and the post-pandemic influenza season: the Nordic experience.

• Published in: Eurosurveillance
• Main Authors: Gil Cuesta, Julita, Aavitsland, Preben, Englund, Hélène, Gudlaugsson, Ólafur, Hauge, Siri Helene, Lyytikäinen, Outi, Sigmundsdóttir, Guðrún, Tegnell, Anders, Virtanen, Mikko, Krause, Tyra Grove
• Other Authors: 1 Statens Serum Inst, DK-2300 Copenhagen, Denmark 2 Epidemi, Kristiansand, Norway 3 Publ Hlth Agcy Sweden, Stockholm, Sweden 4 Ctr Hlth Secur & Communicable Dis Control, Reykjavik, Iceland Show more 5 Norwegian Inst Publ Hlth, Oslo, Norway Show more 6 Natl Inst Hlth & Welf, Helsinki, Finland Show more 7 Ctr Dis Prevent & Control ECDC, Stockholm, Sweden
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Centre for Disease Prevention and Control (ECDC) 2019
• Subjects: Pandemics; influenza A(H1N1)pdm09; influenza A(H3N2); influenza B virus; influenza virus; intensive care units; vaccines and immunisation; Bólusetningar; Inflúensa; Influenza Vaccines; Norway; Iceland
• Online Access: http://hdl.handle.net/2336/621237; https://doi.org/10.2807/1560-7917.ES.2016.21.16.30208

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Download During the 2009/10 influenza A(H1N1)pdm09 pandemic, the five Nordic countries adopted different approaches to pandemic vaccination. We compared pandemic vaccination strategies and severe influenza outcomes, in seasons 2009/10 and 2010/11 in these countries with similar influenza surveillance systems. We calculated the cumulative pandemic vaccination coverage in 2009/10 and cumulative incidence rates of laboratory confirmed A(H1N1)pdm09 infections, intensive care unit (ICU) admissions and deaths in 2009/10 and 2010/11. We estimated incidence risk ratios (IRR) in a Poisson regression model to compare those indicators between Denmark and the other countries. The vaccination coverage was lower in Denmark (6.1%) compared with Finland (48.2%), Iceland (44.1%), Norway (41.3%) and Sweden (60.0%). In 2009/10 Denmark had a similar cumulative incidence of A(H1N1)pdm09 ICU admissions and deaths compared with the other countries. In 2010/11 Denmark had a significantly higher cumulative incidence of A(H1N1)pdm09 ICU admissions (IRR: 2.4; 95% confidence interval (CI): 1.9-3.0) and deaths (IRR: 8.3; 95% CI: 5.1-13.5). Compared with Denmark, the other countries had higher pandemic vaccination coverage and experienced less A(H1N1)pdm09-related severe outcomes in 2010/11. Pandemic vaccination may have had an impact on severe influenza outcomes in the post-pandemic season. Surveillance of severe outcomes may be used to compare the impact of influenza between seasons and support different vaccination strategies.