Epidemiologic and virologic assessment of the 2009 influenza A (H1N1) pandemic on selected temperate countries in the Southern Hemisphere: Argentina, Australia, Chile, New Zealand and South Africa

Item Type:	Article
Title:	Epidemiologic and virologic assessment of the 2009 influenza A (H1N1) pandemic on selected temperate countries in the Southern Hemisphere: Argentina, Australia, Chile, New Zealand and South Africa
Creators Name:	Van Kerkhove, M.D. and Mounts, A.W. and Mall, S. and Vandemaele, K.A. and Chamberland, M. and dos Santos, T. and Fitzner, J. and Widdowson, M.A. and Michalove, J. and Bresee, J. and Olsen, S.J. and Quick, L. and Baumeister, E. and Carlino, L.O. and Savy, V. and Uez, O. and Owen, R. and Ghani, F. and Paterson, B. and Forde, A. and Fasce, R. and Torres, G. and Andrade, W. and Bustos, P. and Mora, J. and Gonzalez, C. and Olea, A. and Sotomayor, V. and Najera De Ferrari, M. and Burgos, A. and Hunt, D. and Huang, Q.S. and Jennings, L.C. and Macfarlane, M. and Lopez, L.D. and McArthur, C. and Cohen, C. and Archer, B. and Blumberg, L. and Cengimbo, A. and Makunga, C. and McAnerney, J. and Msimang, V. and Naidoo, D. and Puren, A. and Schoub, B. and Thomas, J. and Venter, M.
Abstract:	Introduction and Setting: Our analysis compares the most comprehensive epidemiologic and virologic surveillance data compiled to date for laboratory-confirmed H1N1pdm patients between 1 April 2009 - 31 January 2010 from five temperate countries in the Southern Hemisphere-Argentina, Australia, Chile, New Zealand, and South Africa. Objective: We evaluate transmission dynamics, indicators of severity, and describe the co-circulation of H1N1pdm with seasonal influenza viruses. Results: In the five countries, H1N1pdm became the predominant influenza strain within weeks of initial detection. South Africa was unique, first experiencing a seasonal H3N2 wave, followed by a distinct H1N1pdm wave. Compared with the 2007 and 2008 influenza seasons, the peak of influenza-like illness (ILI) activity in four of the five countries was 3-6 times higher with peak ILI consultation rates ranging from 35/1,000 consultations/week in Australia to 275/100,000 population/week in New Zealand. Transmission was similar in all countries with the reproductive rate ranging from 1.2-1.6. The median age of patients in all countries increased with increasing severity of disease, 4-14% of all hospitalized cases required critical care, and 26-68% of fatal patients were reported to have ≥1 chronic medical condition. Compared with seasonal influenza, there was a notable downward shift in age among severe cases with the highest population-based hospitalization rates among children <5 years old. National population-based mortality rates ranged from 0.8-1.5/100,000. Conclusions: The difficulty experienced in tracking the progress of the pandemic globally, estimating its severity early on, and comparing information across countries argues for improved routine surveillance and standardization of investigative approaches and data reporting methods.
Keywords:	H1N1, Influenza Circulation, Pandemic, Severity, Southern Hemisphere, Transmission
Source:	Influenza and Other Respiratory Viruses
ISSN:	1750-2640
Publisher:	Wiley-Blackwell
Volume:	5
Number:	6
Page Range:	e487-e498
Date:	November 2011
Official Publication:	https://doi.org/10.1111/j.1750-2659.2011.00249.x
PubMed:	View item in PubMed

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